diff --git a/src/registrar/admin.py b/src/registrar/admin.py
index 1b6e2de6a..e89147b11 100644
--- a/src/registrar/admin.py
+++ b/src/registrar/admin.py
@@ -1367,6 +1367,8 @@ class UserDomainRoleAdmin(ListHeaderAdmin, ImportExportModelAdmin):
 
     autocomplete_fields = ["user", "domain"]
 
+    change_form_template = "django/admin/user_domain_role_change_form.html"
+
     # Fixes a bug where non-superusers are redirected to the main page
     def delete_view(self, request, object_id, extra_context=None):
         """Custom delete_view implementation that specifies redirect behaviour"""
@@ -1500,7 +1502,7 @@ class DomainInvitationAdmin(BaseInvitationAdmin):
 
     autocomplete_fields = ["domain"]
 
-    change_form_template = "django/admin/email_clipboard_change_form.html"
+    change_form_template = "django/admin/domain_invitation_change_form.html"
 
     # Select domain invitations to change -> Domain invitations
     def changelist_view(self, request, extra_context=None):
diff --git a/src/registrar/assets/js/uswds-edited.js b/src/registrar/assets/js/uswds-edited.js
index f59417b41..9d4dd2e51 100644
--- a/src/registrar/assets/js/uswds-edited.js
+++ b/src/registrar/assets/js/uswds-edited.js
@@ -29,6 +29,7 @@
  *  - tooltip dynamic content updated to include nested element (for better sizing control)
  *  - modal exposed to window to be accessible in other js files
  *  - fixed bug in createHeaderButton which added newlines to header button tooltips
+ *  - modified combobox to handle error class
  */
 
 if ("document" in window.self) {
@@ -1213,6 +1214,11 @@ const enhanceComboBox = _comboBoxEl => {
   input.setAttribute("class", INPUT_CLASS);
   input.setAttribute("type", "text");
   input.setAttribute("role", "combobox");
+  // DOTGOV - handle error class for combobox
+  // Check if 'usa-input--error' exists in selectEl and add it to input if true
+  if (selectEl.classList.contains('usa-input--error')) {
+    input.classList.add('usa-input--error');
+  }
   additionalAttributes.forEach(attr => Object.keys(attr).forEach(key => {
     const value = Sanitizer.escapeHTML`${attr[key]}`;
     input.setAttribute(key, value);
diff --git a/src/registrar/assets/src/js/getgov/combobox.js b/src/registrar/assets/src/js/getgov/combobox.js
deleted file mode 100644
index 36b7aa0ad..000000000
--- a/src/registrar/assets/src/js/getgov/combobox.js
+++ /dev/null
@@ -1,113 +0,0 @@
-import { hideElement, showElement } from './helpers.js';
-
-export function loadInitialValuesForComboBoxes() {
-  var overrideDefaultClearButton = true;
-  var isTyping = false;
-
-  document.addEventListener('DOMContentLoaded', (event) => {
-    handleAllComboBoxElements();
-  });
-
-  function handleAllComboBoxElements() {
-    const comboBoxElements = document.querySelectorAll(".usa-combo-box");
-    comboBoxElements.forEach(comboBox => {
-      const input = comboBox.querySelector("input");
-      const select = comboBox.querySelector("select");
-      if (!input || !select) {
-        console.warn("No combobox element found");
-        return;
-      }
-      // Set the initial value of the combobox
-      let initialValue = select.getAttribute("data-default-value");
-      let clearInputButton = comboBox.querySelector(".usa-combo-box__clear-input");
-      if (!clearInputButton) {
-        console.warn("No clear element found");
-        return;
-      }
-
-      // Override the default clear button behavior such that it no longer clears the input,
-      // it just resets to the data-initial-value.
-      // Due to the nature of how uswds works, this is slightly hacky.
-      // Use a MutationObserver to watch for changes in the dropdown list
-      const dropdownList = comboBox.querySelector(`#${input.id}--list`);
-      const observer = new MutationObserver(function(mutations) {
-          mutations.forEach(function(mutation) {
-              if (mutation.type === "childList") {
-                addBlankOption(clearInputButton, dropdownList, initialValue);
-              }
-          });
-      });
-
-      // Configure the observer to watch for changes in the dropdown list
-      const config = { childList: true, subtree: true };
-      observer.observe(dropdownList, config);
-
-      // Input event listener to detect typing
-      input.addEventListener("input", () => {
-        isTyping = true;
-      });
-
-      // Blur event listener to reset typing state
-      input.addEventListener("blur", () => {
-        isTyping = false;
-      });
-
-      // Hide the reset button when there is nothing to reset.
-      // Do this once on init, then everytime a change occurs.
-      updateClearButtonVisibility(select, initialValue, clearInputButton)
-      select.addEventListener("change", () => {
-        updateClearButtonVisibility(select, initialValue, clearInputButton)
-      });
-
-      // Change the default input behaviour - have it reset to the data default instead
-      clearInputButton.addEventListener("click", (e) => {
-        if (overrideDefaultClearButton && initialValue) {
-          e.preventDefault();
-          e.stopPropagation();
-          input.click();
-          // Find the dropdown option with the desired value
-          const dropdownOptions = document.querySelectorAll(".usa-combo-box__list-option");
-          if (dropdownOptions) {
-            dropdownOptions.forEach(option => {
-                if (option.getAttribute("data-value") === initialValue) {
-                    // Simulate a click event on the dropdown option
-                    option.click();
-                }
-            });
-          }
-        }
-      });
-    });
-  }
-
-  function updateClearButtonVisibility(select, initialValue, clearInputButton) {
-    if (select.value === initialValue) {
-      hideElement(clearInputButton);
-    }else {
-      showElement(clearInputButton)
-    }
-  }
-
-  function addBlankOption(clearInputButton, dropdownList, initialValue) {
-    if (dropdownList && !dropdownList.querySelector('[data-value=""]') && !isTyping) {
-        const blankOption = document.createElement("li");
-        blankOption.setAttribute("role", "option");
-        blankOption.setAttribute("data-value", "");
-        blankOption.classList.add("usa-combo-box__list-option");
-        if (!initialValue){
-          blankOption.classList.add("usa-combo-box__list-option--selected")
-        }
-        blankOption.textContent = "⎯";
-
-        dropdownList.insertBefore(blankOption, dropdownList.firstChild);
-        blankOption.addEventListener("click", (e) => {
-          e.preventDefault();
-          e.stopPropagation();
-          overrideDefaultClearButton = false;
-          // Trigger the default clear behavior
-          clearInputButton.click();
-          overrideDefaultClearButton = true;
-        });
-    }
-  }
-}
diff --git a/src/registrar/assets/src/js/getgov/main.js b/src/registrar/assets/src/js/getgov/main.js
index 6ff402aa4..a077da929 100644
--- a/src/registrar/assets/src/js/getgov/main.js
+++ b/src/registrar/assets/src/js/getgov/main.js
@@ -3,7 +3,6 @@ import { initDomainValidators } from './domain-validators.js';
 import { initFormsetsForms, triggerModalOnDsDataForm, nameserversFormListener } from './formset-forms.js';
 import { initializeUrbanizationToggle } from './urbanization.js';
 import { userProfileListener, finishUserSetupListener } from './user-profile.js';
-import { loadInitialValuesForComboBoxes } from './combobox.js';
 import { handleRequestingEntityFieldset } from './requesting-entity.js';
 import { initDomainsTable } from './table-domains.js';
 import { initDomainRequestsTable } from './table-domain-requests.js';
@@ -31,8 +30,6 @@ initializeUrbanizationToggle();
 userProfileListener();
 finishUserSetupListener();
 
-loadInitialValuesForComboBoxes();
-
 handleRequestingEntityFieldset();
 
 initDomainsTable();
diff --git a/src/registrar/assets/src/js/getgov/requesting-entity.js b/src/registrar/assets/src/js/getgov/requesting-entity.js
index 3bcdcd35c..833eab2f8 100644
--- a/src/registrar/assets/src/js/getgov/requesting-entity.js
+++ b/src/registrar/assets/src/js/getgov/requesting-entity.js
@@ -9,15 +9,15 @@ export function handleRequestingEntityFieldset() {
     const formPrefix = "portfolio_requesting_entity";
     const radioFieldset = document.getElementById(`id_${formPrefix}-requesting_entity_is_suborganization__fieldset`);
     const radios = radioFieldset?.querySelectorAll(`input[name="${formPrefix}-requesting_entity_is_suborganization"]`);
-    const select = document.getElementById(`id_${formPrefix}-sub_organization`);
-    const selectParent = select?.parentElement;
+    const input = document.getElementById(`id_${formPrefix}-sub_organization`);
+    const inputGrandParent = input?.parentElement?.parentElement;
+    const select = input?.previousElementSibling;
     const suborgContainer = document.getElementById("suborganization-container");
     const suborgDetailsContainer = document.getElementById("suborganization-container__details");
     const suborgAddtlInstruction = document.getElementById("suborganization-addtl-instruction");
-    const subOrgCreateNewOption = document.getElementById("option-to-add-suborg")?.value;
     // Make sure all crucial page elements exist before proceeding.
     // This more or less ensures that we are on the Requesting Entity page, and not elsewhere.
-    if (!radios || !select || !selectParent || !suborgContainer || !suborgDetailsContainer) return;
+    if (!radios || !input || !select || !inputGrandParent || !suborgContainer || !suborgDetailsContainer) return;
 
     // requestingSuborganization: This just broadly determines if they're requesting a suborg at all
     // requestingNewSuborganization: This variable determines if the user is trying to *create* a new suborganization or not.
@@ -27,8 +27,8 @@ export function handleRequestingEntityFieldset() {
     function toggleSuborganization(radio=null) {
         if (radio != null) requestingSuborganization = radio?.checked && radio.value === "True";
         requestingSuborganization ? showElement(suborgContainer) : hideElement(suborgContainer);
-        if (select.options.length == 2) { // --Select-- and other are the only options
-            hideElement(selectParent); // Hide the select drop down and indicate requesting new suborg
+        if (select.options.length == 1) { // other is the only option
+            hideElement(inputGrandParent); // Hide the combo box and indicate requesting new suborg
             hideElement(suborgAddtlInstruction); // Hide additional instruction related to the list
             requestingNewSuborganization.value = "True";
         } else {
@@ -37,11 +37,6 @@ export function handleRequestingEntityFieldset() {
         requestingNewSuborganization.value === "True" ? showElement(suborgDetailsContainer) : hideElement(suborgDetailsContainer);
     }
 
-    // Add fake "other" option to sub_organization select
-    if (select && !Array.from(select.options).some(option => option.value === "other")) {
-        select.add(new Option(subOrgCreateNewOption, "other"));
-    }
-
     if (requestingNewSuborganization.value === "True") {
         select.value = "other";
     }
diff --git a/src/registrar/forms/domain.py b/src/registrar/forms/domain.py
index 699efe63b..05eb90db3 100644
--- a/src/registrar/forms/domain.py
+++ b/src/registrar/forms/domain.py
@@ -4,6 +4,7 @@ import logging
 from django import forms
 from django.core.validators import MinValueValidator, MaxValueValidator, RegexValidator, MaxLengthValidator
 from django.forms import formset_factory
+from registrar.forms.utility.combobox import ComboboxWidget
 from registrar.models import DomainRequest, FederalAgency
 from phonenumber_field.widgets import RegionalPhoneNumberWidget
 from registrar.models.suborganization import Suborganization
@@ -161,9 +162,10 @@ class DomainSuborganizationForm(forms.ModelForm):
     """Form for updating the suborganization"""
 
     sub_organization = forms.ModelChoiceField(
+        label="Suborganization name",
         queryset=Suborganization.objects.none(),
         required=False,
-        widget=forms.Select(),
+        widget=ComboboxWidget,
     )
 
     class Meta:
@@ -178,20 +180,6 @@ class DomainSuborganizationForm(forms.ModelForm):
         portfolio = self.instance.portfolio if self.instance else None
         self.fields["sub_organization"].queryset = Suborganization.objects.filter(portfolio=portfolio)
 
-        # Set initial value
-        if self.instance and self.instance.sub_organization:
-            self.fields["sub_organization"].initial = self.instance.sub_organization
-
-        # Set custom form label
-        self.fields["sub_organization"].label = "Suborganization name"
-
-        # Use the combobox rather than the regular select widget
-        self.fields["sub_organization"].widget.template_name = "django/forms/widgets/combobox.html"
-
-        # Set data-default-value attribute
-        if self.instance and self.instance.sub_organization:
-            self.fields["sub_organization"].widget.attrs["data-default-value"] = self.instance.sub_organization.pk
-
 
 class BaseNameserverFormset(forms.BaseFormSet):
     def clean(self):
@@ -456,6 +444,13 @@ class DomainSecurityEmailForm(forms.Form):
 class DomainOrgNameAddressForm(forms.ModelForm):
     """Form for updating the organization name and mailing address."""
 
+    # for federal agencies we also want to know the top-level agency.
+    federal_agency = forms.ModelChoiceField(
+        label="Federal agency",
+        required=False,
+        queryset=FederalAgency.objects.all(),
+        widget=ComboboxWidget,
+    )
     zipcode = forms.CharField(
         label="Zip code",
         validators=[
@@ -469,6 +464,16 @@ class DomainOrgNameAddressForm(forms.ModelForm):
         },
     )
 
+    state_territory = forms.ChoiceField(
+        label="State, territory, or military post",
+        required=True,
+        choices=DomainInformation.StateTerritoryChoices.choices,
+        error_messages={
+            "required": ("Select the state, territory, or military post where your organization is located.")
+        },
+        widget=ComboboxWidget(attrs={"required": True}),
+    )
+
     class Meta:
         model = DomainInformation
         fields = [
@@ -486,25 +491,12 @@ class DomainOrgNameAddressForm(forms.ModelForm):
             "organization_name": {"required": "Enter the name of your organization."},
             "address_line1": {"required": "Enter the street address of your organization."},
             "city": {"required": "Enter the city where your organization is located."},
-            "state_territory": {
-                "required": "Select the state, territory, or military post where your organization is located."
-            },
         }
         widgets = {
-            # We need to set the required attributed for State/territory
-            # because for this fields we are creating an individual
-            # instance of the Select. For the other fields we use the for loop to set
-            # the class's required attribute to true.
             "organization_name": forms.TextInput,
             "address_line1": forms.TextInput,
             "address_line2": forms.TextInput,
             "city": forms.TextInput,
-            "state_territory": forms.Select(
-                attrs={
-                    "required": True,
-                },
-                choices=DomainInformation.StateTerritoryChoices.choices,
-            ),
             "urbanization": forms.TextInput,
         }
 
diff --git a/src/registrar/forms/domain_request_wizard.py b/src/registrar/forms/domain_request_wizard.py
index ccdbb17ba..7c9dcb180 100644
--- a/src/registrar/forms/domain_request_wizard.py
+++ b/src/registrar/forms/domain_request_wizard.py
@@ -7,6 +7,7 @@ from django import forms
 from django.core.validators import RegexValidator, MaxLengthValidator
 from django.utils.safestring import mark_safe
 
+from registrar.forms.utility.combobox import ComboboxWidget
 from registrar.forms.utility.wizard_form_helper import (
     RegistrarForm,
     RegistrarFormSet,
@@ -43,7 +44,7 @@ class RequestingEntityForm(RegistrarForm):
         label="Suborganization name",
         required=False,
         queryset=Suborganization.objects.none(),
-        empty_label="--Select--",
+        widget=ComboboxWidget,
     )
     requested_suborganization = forms.CharField(
         label="Requested suborganization",
@@ -56,22 +57,44 @@ class RequestingEntityForm(RegistrarForm):
     suborganization_state_territory = forms.ChoiceField(
         label="State, territory, or military post",
         required=False,
-        choices=[("", "--Select--")] + DomainRequest.StateTerritoryChoices.choices,
+        choices=DomainRequest.StateTerritoryChoices.choices,
+        widget=ComboboxWidget,
     )
 
     def __init__(self, *args, **kwargs):
-        """Override of init to add the suborganization queryset"""
+        """Override of init to add the suborganization queryset and 'other' option"""
         super().__init__(*args, **kwargs)
 
         if self.domain_request.portfolio:
-            self.fields["sub_organization"].queryset = Suborganization.objects.filter(
-                portfolio=self.domain_request.portfolio
-            )
+            # Fetch the queryset for the portfolio
+            queryset = Suborganization.objects.filter(portfolio=self.domain_request.portfolio)
+            # set the queryset appropriately so that post can validate against queryset
+            self.fields["sub_organization"].queryset = queryset
+
+            # Modify the choices to include "other" so that form can display options properly
+            self.fields["sub_organization"].choices = [(obj.id, str(obj)) for obj in queryset] + [
+                ("other", "Other (enter your suborganization manually)")
+            ]
+
+    @classmethod
+    def from_database(cls, obj: DomainRequest | Contact | None):
+        """Returns a dict of form field values gotten from `obj`.
+        Overrides RegistrarForm method in order to set sub_organization to 'other'
+        on GETs of the RequestingEntityForm."""
+        if obj is None:
+            return {}
+        # get the domain request as a dict, per usual method
+        domain_request_dict = {name: getattr(obj, name) for name in cls.declared_fields.keys()}  # type: ignore
+
+        # set sub_organization to 'other' if is_requesting_new_suborganization is True
+        if isinstance(obj, DomainRequest) and obj.is_requesting_new_suborganization():
+            domain_request_dict["sub_organization"] = "other"
+
+        return domain_request_dict
 
     def clean_sub_organization(self):
         """On suborganization clean, set the suborganization value to None if the user is requesting
         a custom suborganization (as it doesn't exist yet)"""
-
         # If it's a new suborganization, return None (equivalent to selecting nothing)
         if self.cleaned_data.get("is_requesting_new_suborganization"):
             return None
@@ -94,41 +117,60 @@ class RequestingEntityForm(RegistrarForm):
         return name
 
     def full_clean(self):
-        """Validation logic to remove the custom suborganization value before clean is triggered.
+        """Validation logic to temporarily remove the custom suborganization value before clean is triggered.
         Without this override, the form will throw an 'invalid option' error."""
-        # Remove the custom other field before cleaning
-        data = self.data.copy() if self.data else None
+        # Ensure self.data is not None before proceeding
+        if self.data:
+            # handle case where form has been submitted
+            # Create a copy of the data for manipulation
+            data = self.data.copy()
 
-        # Remove the 'other' value from suborganization if it exists.
-        # This is a special value that tracks if the user is requesting a new suborg.
-        suborganization = self.data.get("portfolio_requesting_entity-sub_organization")
-        if suborganization and "other" in suborganization:
-            data["portfolio_requesting_entity-sub_organization"] = ""
+            # Retrieve sub_organization and store in _original_suborganization
+            suborganization = data.get("portfolio_requesting_entity-sub_organization")
+            self._original_suborganization = suborganization
+            # If the original value was "other", clear it for validation
+            if self._original_suborganization == "other":
+                data["portfolio_requesting_entity-sub_organization"] = ""
 
-        # Set the modified data back to the form
-        self.data = data
+            # Set the modified data back to the form
+            self.data = data
+        else:
+            # handle case of a GET
+            suborganization = None
+            if self.initial and "sub_organization" in self.initial:
+                suborganization = self.initial["sub_organization"]
+
+            # Check if is_requesting_new_suborganization is True
+            is_requesting_new_suborganization = False
+            if self.initial and "is_requesting_new_suborganization" in self.initial:
+                # Call the method if it exists
+                is_requesting_new_suborganization = self.initial["is_requesting_new_suborganization"]()
+
+            # Determine if "other" should be set
+            if is_requesting_new_suborganization and suborganization is None:
+                self._original_suborganization = "other"
+            else:
+                self._original_suborganization = suborganization
 
         # Call the parent's full_clean method
         super().full_clean()
 
+        # Restore "other" if there are errors
+        if self.errors:
+            self.data["portfolio_requesting_entity-sub_organization"] = self._original_suborganization
+
     def clean(self):
-        """Custom clean implementation to handle our desired logic flow for suborganization.
-        Given that these fields often rely on eachother, we need to do this in the parent function."""
+        """Custom clean implementation to handle our desired logic flow for suborganization."""
         cleaned_data = super().clean()
 
-        # Do some custom error validation if the requesting entity is a suborg.
-        # Otherwise, just validate as normal.
-        suborganization = self.cleaned_data.get("sub_organization")
-        is_requesting_new_suborganization = self.cleaned_data.get("is_requesting_new_suborganization")
-
-        # Get the value of the yes/no checkbox from RequestingEntityYesNoForm.
-        # Since self.data stores this as a string, we need to convert "True" => True.
+        # Get the cleaned data
+        suborganization = cleaned_data.get("sub_organization")
+        is_requesting_new_suborganization = cleaned_data.get("is_requesting_new_suborganization")
         requesting_entity_is_suborganization = self.data.get(
             "portfolio_requesting_entity-requesting_entity_is_suborganization"
         )
         if requesting_entity_is_suborganization == "True":
             if is_requesting_new_suborganization:
-                # Validate custom suborganization fields
                 if not cleaned_data.get("requested_suborganization") and "requested_suborganization" not in self.errors:
                     self.add_error("requested_suborganization", "Enter the name of your suborganization.")
                 if not cleaned_data.get("suborganization_city"):
@@ -141,6 +183,12 @@ class RequestingEntityForm(RegistrarForm):
             elif not suborganization:
                 self.add_error("sub_organization", "Suborganization is required.")
 
+        # If there are errors, restore the "other" value for rendering
+        if self.errors and getattr(self, "_original_suborganization", None) == "other":
+            self.cleaned_data["sub_organization"] = self._original_suborganization
+        elif not self.data and getattr(self, "_original_suborganization", None) == "other":
+            self.cleaned_data["sub_organization"] = self._original_suborganization
+
         return cleaned_data
 
 
@@ -274,7 +322,7 @@ class OrganizationContactForm(RegistrarForm):
         # uncomment to see if modelChoiceField can be an arg later
         required=False,
         queryset=FederalAgency.objects.exclude(agency__in=excluded_agencies),
-        empty_label="--Select--",
+        widget=ComboboxWidget,
     )
     organization_name = forms.CharField(
         label="Organization name",
@@ -294,10 +342,11 @@ class OrganizationContactForm(RegistrarForm):
     )
     state_territory = forms.ChoiceField(
         label="State, territory, or military post",
-        choices=[("", "--Select--")] + DomainRequest.StateTerritoryChoices.choices,
+        choices=DomainRequest.StateTerritoryChoices.choices,
         error_messages={
             "required": ("Select the state, territory, or military post where your organization is located.")
         },
+        widget=ComboboxWidget,
     )
     zipcode = forms.CharField(
         label="Zip code",
diff --git a/src/registrar/forms/portfolio.py b/src/registrar/forms/portfolio.py
index 0a8c4d623..e57b56c4f 100644
--- a/src/registrar/forms/portfolio.py
+++ b/src/registrar/forms/portfolio.py
@@ -6,6 +6,7 @@ from django.core.validators import RegexValidator
 from django.core.validators import MaxLengthValidator
 from django.utils.safestring import mark_safe
 
+from registrar.forms.utility.combobox import ComboboxWidget
 from registrar.models import (
     PortfolioInvitation,
     UserPortfolioPermission,
@@ -33,6 +34,15 @@ class PortfolioOrgAddressForm(forms.ModelForm):
             "required": "Enter a 5-digit or 9-digit zip code, like 12345 or 12345-6789.",
         },
     )
+    state_territory = forms.ChoiceField(
+        label="State, territory, or military post",
+        required=True,
+        choices=DomainInformation.StateTerritoryChoices.choices,
+        error_messages={
+            "required": ("Select the state, territory, or military post where your organization is located.")
+        },
+        widget=ComboboxWidget(attrs={"required": True}),
+    )
 
     class Meta:
         model = Portfolio
@@ -47,25 +57,12 @@ class PortfolioOrgAddressForm(forms.ModelForm):
         error_messages = {
             "address_line1": {"required": "Enter the street address of your organization."},
             "city": {"required": "Enter the city where your organization is located."},
-            "state_territory": {
-                "required": "Select the state, territory, or military post where your organization is located."
-            },
             "zipcode": {"required": "Enter a 5-digit or 9-digit zip code, like 12345 or 12345-6789."},
         }
         widgets = {
-            # We need to set the required attributed for State/territory
-            # because for this fields we are creating an individual
-            # instance of the Select. For the other fields we use the for loop to set
-            # the class's required attribute to true.
             "address_line1": forms.TextInput,
             "address_line2": forms.TextInput,
             "city": forms.TextInput,
-            "state_territory": forms.Select(
-                attrs={
-                    "required": True,
-                },
-                choices=DomainInformation.StateTerritoryChoices.choices,
-            ),
             # "urbanization": forms.TextInput,
         }
 
diff --git a/src/registrar/forms/utility/combobox.py b/src/registrar/forms/utility/combobox.py
new file mode 100644
index 000000000..277aec4f3
--- /dev/null
+++ b/src/registrar/forms/utility/combobox.py
@@ -0,0 +1,5 @@
+from django.forms import Select
+
+
+class ComboboxWidget(Select):
+    template_name = "django/forms/widgets/combobox.html"
diff --git a/src/registrar/models/domain.py b/src/registrar/models/domain.py
index 6bd8278a1..cb481db7a 100644
--- a/src/registrar/models/domain.py
+++ b/src/registrar/models/domain.py
@@ -4,9 +4,9 @@ import ipaddress
 import re
 from datetime import date, timedelta
 from typing import Optional
+from django.db import transaction
 from django_fsm import FSMField, transition, TransitionNotAllowed  # type: ignore
-
-from django.db import models
+from django.db import models, IntegrityError
 from django.utils import timezone
 from typing import Any
 from registrar.models.host import Host
@@ -1329,14 +1329,14 @@ class Domain(TimeStampedModel, DomainHelper):
 
     def get_default_administrative_contact(self):
         """Gets the default administrative contact."""
-        logger.info("get_default_security_contact() -> Adding administrative security contact")
+        logger.info("get_default_administrative_contact() -> Adding default administrative contact")
         contact = PublicContact.get_default_administrative()
         contact.domain = self
         return contact
 
     def get_default_technical_contact(self):
         """Gets the default technical contact."""
-        logger.info("get_default_security_contact() -> Adding technical security contact")
+        logger.info("get_default_security_contact() -> Adding default technical contact")
         contact = PublicContact.get_default_technical()
         contact.domain = self
         return contact
@@ -1678,9 +1678,11 @@ class Domain(TimeStampedModel, DomainHelper):
         for domainContact in contact_data:
             req = commands.InfoContact(id=domainContact.contact)
             data = registry.send(req, cleaned=True).res_data[0]
+            logger.info(f"_fetch_contacts => this is the data: {data}")
 
             # Map the object we recieved from EPP to a PublicContact
             mapped_object = self.map_epp_contact_to_public_contact(data, domainContact.contact, domainContact.type)
+            logger.info(f"_fetch_contacts => mapped_object: {mapped_object}")
 
             # Find/create it in the DB
             in_db = self._get_or_create_public_contact(mapped_object)
@@ -1871,8 +1873,9 @@ class Domain(TimeStampedModel, DomainHelper):
         missingSecurity = True
         missingTech = True
 
-        if len(cleaned.get("_contacts")) < 3:
-            for contact in cleaned.get("_contacts"):
+        contacts = cleaned.get("_contacts", [])
+        if len(contacts) < 3:
+            for contact in contacts:
                 if contact.type == PublicContact.ContactTypeChoices.ADMINISTRATIVE:
                     missingAdmin = False
                 if contact.type == PublicContact.ContactTypeChoices.SECURITY:
@@ -1891,6 +1894,11 @@ class Domain(TimeStampedModel, DomainHelper):
                 technical_contact = self.get_default_technical_contact()
                 technical_contact.save()
 
+            logger.info(
+                "_add_missing_contacts_if_unknown => Adding contacts. Values are "
+                f"missingAdmin: {missingAdmin}, missingSecurity: {missingSecurity}, missingTech: {missingTech}"
+            )
+
     def _fetch_cache(self, fetch_hosts=False, fetch_contacts=False):
         """Contact registry for info about a domain."""
         try:
@@ -2104,8 +2112,21 @@ class Domain(TimeStampedModel, DomainHelper):
         # Save to DB if it doesn't exist already.
         if db_contact.count() == 0:
             # Doesn't run custom save logic, just saves to DB
-            public_contact.save(skip_epp_save=True)
-            logger.info(f"Created a new PublicContact: {public_contact}")
+            try:
+                with transaction.atomic():
+                    public_contact.save(skip_epp_save=True)
+                    logger.info(f"Created a new PublicContact: {public_contact}")
+            except IntegrityError as err:
+                logger.error(
+                    f"_get_or_create_public_contact() => tried to create a duplicate public contact: {err}",
+                    exc_info=True,
+                )
+                return PublicContact.objects.get(
+                    registry_id=public_contact.registry_id,
+                    contact_type=public_contact.contact_type,
+                    domain=self,
+                )
+
             # Append the item we just created
             return public_contact
 
@@ -2115,7 +2136,7 @@ class Domain(TimeStampedModel, DomainHelper):
         if existing_contact.email != public_contact.email or existing_contact.registry_id != public_contact.registry_id:
             existing_contact.delete()
             public_contact.save()
-            logger.warning("Requested PublicContact is out of sync " "with DB.")
+            logger.warning("Requested PublicContact is out of sync with DB.")
             return public_contact
 
         # If it already exists, we can assume that the DB instance was updated during set, so we should just use that.
diff --git a/src/registrar/templates/django/admin/domain_invitation_change_form.html b/src/registrar/templates/django/admin/domain_invitation_change_form.html
new file mode 100644
index 000000000..6ce6ed0d1
--- /dev/null
+++ b/src/registrar/templates/django/admin/domain_invitation_change_form.html
@@ -0,0 +1,14 @@
+{% extends 'django/admin/email_clipboard_change_form.html' %}
+{% load custom_filters %}
+{% load i18n static %}
+
+{% block content_subtitle %}
+    <div class="usa-alert usa-alert--info usa-alert--slim">
+        <div class="usa-alert__body margin-left-1 maxw-none">
+            <p class="usa-alert__text maxw-none">
+                If you add someone to a domain here, it will trigger emails to the invitee and all managers of the domain when you click "save." If you don't want to trigger those emails, use the <a class="usa-link" href="{% url 'admin:registrar_userdomainrole_changelist' %}">User domain roles permissions table</a> instead.
+            </p>
+        </div>
+    </div>
+    {{ block.super }}
+{% endblock %}
diff --git a/src/registrar/templates/django/admin/user_domain_role_change_form.html b/src/registrar/templates/django/admin/user_domain_role_change_form.html
new file mode 100644
index 000000000..d8c298bc1
--- /dev/null
+++ b/src/registrar/templates/django/admin/user_domain_role_change_form.html
@@ -0,0 +1,14 @@
+{% extends 'django/admin/email_clipboard_change_form.html' %}
+{% load custom_filters %}
+{% load i18n static %}
+
+{% block content_subtitle %}
+    <div class="usa-alert usa-alert--info usa-alert--slim">
+        <div class="usa-alert__body margin-left-1 maxw-none">
+            <p class="usa-alert__text maxw-none">
+                If you add someone to a domain here, it will not trigger any emails. To trigger emails, use the <a class="usa-link" href="{% url 'admin:registrar_domaininvitation_changelist' %}">User Domain Role invitations table</a> instead.
+            </p>
+        </div>
+    </div>
+    {{ block.super }}
+{% endblock %}
diff --git a/src/registrar/templates/django/forms/widgets/combobox.html b/src/registrar/templates/django/forms/widgets/combobox.html
index 7ff31945b..02cd4e35e 100644
--- a/src/registrar/templates/django/forms/widgets/combobox.html
+++ b/src/registrar/templates/django/forms/widgets/combobox.html
@@ -11,6 +11,7 @@ for now we just carry the attribute to both the parent element and the select.
         {{ name }}="{{ value }}"
     {% endif %}
 {% endfor %}
+data-default-value="{% for group_name, group_choices, group_index in widget.optgroups %}{% for option in group_choices %}{% if option.selected %}{{ option.value }}{% endif %}{% endfor %}{% endfor %}"
 >
-    {% include "django/forms/widgets/select.html" %}
+    {% include "django/forms/widgets/select.html" with is_combobox=True %}
 </div>
diff --git a/src/registrar/templates/django/forms/widgets/select.html b/src/registrar/templates/django/forms/widgets/select.html
index cc62eb91d..db6deafe2 100644
--- a/src/registrar/templates/django/forms/widgets/select.html
+++ b/src/registrar/templates/django/forms/widgets/select.html
@@ -3,6 +3,9 @@
     {# hint: spacing in the class string matters #}
     class="usa-select{% if classes %} {{ classes }}{% endif %}"
     {% include "django/forms/widgets/attrs.html" %}
+    {% if is_combobox %}
+      data-default-value="{% for group_name, group_choices, group_index in widget.optgroups %}{% for option in group_choices %}{% if option.selected %}{{ option.value }}{% endif %}{% endfor %}{% endfor %}"
+    {% endif %}
 >
   {% for group, options, index in widget.optgroups %}
     {% if group %}<optgroup label="{{ group }}">{% endif %}
diff --git a/src/registrar/templates/emails/domain_manager_notification.txt b/src/registrar/templates/emails/domain_manager_notification.txt
new file mode 100644
index 000000000..aa8c6bf34
--- /dev/null
+++ b/src/registrar/templates/emails/domain_manager_notification.txt
@@ -0,0 +1,43 @@
+{% autoescape off %}{# In a text file, we don't want to have HTML entities escaped #}
+Hi,{% if domain_manager and domain_manager.first_name %} {{ domain_manager.first_name }}.{% endif %}
+
+A domain manager was invited to {{ domain.name }}.
+DOMAIN: {{ domain.name }}
+INVITED BY: {{ requestor_email }}
+INVITED ON: {{date}}
+MANAGER INVITED: {{ invited_email_address }}
+
+
+----------------------------------------------------------------
+
+
+NEXT STEPS
+
+The person who received the invitation will become a domain manager once they log in to the
+.gov registrar. They'll need to access the registrar using a Login.gov account that's
+associated with the invited email address.
+
+If you need to cancel this invitation or remove the domain manager (because they've already
+logged in), you can do that by going to this domain in the .gov registrar <https://manage.get.gov/>.
+
+
+WHY DID YOU RECEIVE THIS EMAIL? 
+
+You’re listed as a domain manager for {{ domain.name }}, so you’ll receive a notification whenever
+someone is invited to manage that domain.
+
+If you have questions or concerns, reach out to the person who sent the invitation or reply to this email.
+
+
+THANK YOU
+.Gov helps the public identify official, trusted information. Thank you for using a .gov domain.
+
+----------------------------------------------------------------
+
+The .gov team
+Contact us: <https://get.gov/contact/>
+Learn about .gov <https://get.gov>
+
+The .gov registry is a part of the Cybersecurity and Infrastructure Security Agency
+(CISA) <https://cisa.gov/>
+{% endautoescape %}
diff --git a/src/registrar/templates/emails/domain_manager_notification_subject.txt b/src/registrar/templates/emails/domain_manager_notification_subject.txt
new file mode 100644
index 000000000..0e9918de0
--- /dev/null
+++ b/src/registrar/templates/emails/domain_manager_notification_subject.txt
@@ -0,0 +1 @@
+A domain manager was invited to {{ domain.name }}
\ No newline at end of file
diff --git a/src/registrar/tests/common.py b/src/registrar/tests/common.py
index c0083068d..bb65ef6b1 100644
--- a/src/registrar/tests/common.py
+++ b/src/registrar/tests/common.py
@@ -578,6 +578,13 @@ class MockDb(TestCase):
             creator=cls.custom_superuser, federal_agency=cls.federal_agency_3, organization_type="federal"
         )
 
+        cls.suborganization_1, _ = Suborganization.objects.get_or_create(
+            name="SubOrg 1",
+            portfolio=cls.portfolio_1,
+            city="Nashville",
+            state_territory="TN",
+        )
+
         current_date = get_time_aware_date(datetime(2024, 4, 2))
         # Create start and end dates using timedelta
 
@@ -848,6 +855,7 @@ class MockDb(TestCase):
                 status=DomainRequest.DomainRequestStatus.IN_REVIEW,
                 name="city2.gov",
                 portfolio=cls.portfolio_1,
+                sub_organization=cls.suborganization_1,
             )
             cls.domain_request_3 = completed_domain_request(
                 status=DomainRequest.DomainRequestStatus.STARTED,
@@ -863,6 +871,9 @@ class MockDb(TestCase):
             cls.domain_request_5 = completed_domain_request(
                 status=DomainRequest.DomainRequestStatus.APPROVED,
                 name="city5.gov",
+                requested_suborganization="requested_suborg",
+                suborganization_city="SanFran",
+                suborganization_state_territory="CA",
             )
             cls.domain_request_6 = completed_domain_request(
                 status=DomainRequest.DomainRequestStatus.STARTED,
diff --git a/src/registrar/tests/test_admin.py b/src/registrar/tests/test_admin.py
index 2a7a52a13..036e35a50 100644
--- a/src/registrar/tests/test_admin.py
+++ b/src/registrar/tests/test_admin.py
@@ -166,6 +166,29 @@ class TestDomainInvitationAdmin(TestCase):
         )
         self.assertContains(response, "Show more")
 
+    @less_console_noise_decorator
+    def test_has_change_form_description(self):
+        """Tests if this model has a model description on the change form view"""
+        self.client.force_login(self.superuser)
+
+        domain, _ = Domain.objects.get_or_create(name="systemofadown.com")
+
+        domain_invitation, _ = DomainInvitation.objects.get_or_create(email="toxicity@systemofadown.com", domain=domain)
+
+        response = self.client.get(
+            "/admin/registrar/domaininvitation/{}/change/".format(domain_invitation.pk),
+            follow=True,
+        )
+
+        # Make sure that the page is loaded correctly
+        self.assertEqual(response.status_code, 200)
+
+        # Test for a description snippet
+        self.assertContains(
+            response,
+            "If you add someone to a domain here, it will trigger emails to the invitee and all managers of the domain",
+        )
+
     @less_console_noise_decorator
     def test_get_filters(self):
         """Ensures that our filters are displaying correctly"""
@@ -1957,6 +1980,31 @@ class TestUserDomainRoleAdmin(TestCase):
         )
         self.assertContains(response, "Show more")
 
+    @less_console_noise_decorator
+    def test_has_change_form_description(self):
+        """Tests if this model has a model description on the change form view"""
+        self.client.force_login(self.superuser)
+
+        domain, _ = Domain.objects.get_or_create(name="systemofadown.com")
+
+        user_domain_role, _ = UserDomainRole.objects.get_or_create(
+            user=self.superuser, domain=domain, role=[UserDomainRole.Roles.MANAGER]
+        )
+
+        response = self.client.get(
+            "/admin/registrar/userdomainrole/{}/change/".format(user_domain_role.pk),
+            follow=True,
+        )
+
+        # Make sure that the page is loaded correctly
+        self.assertEqual(response.status_code, 200)
+
+        # Test for a description snippet
+        self.assertContains(
+            response,
+            "If you add someone to a domain here, it will not trigger any emails.",
+        )
+
     def test_domain_sortable(self):
         """Tests if the UserDomainrole sorts by domain correctly"""
         with less_console_noise():
@@ -3442,7 +3490,7 @@ class TestTransferUser(WebTest):
 
     @less_console_noise_decorator
     def test_transfer_user_transfers_user_portfolio_roles_no_error_when_duplicates(self):
-        """Assert that duplicate portfolio user roles do not throw errorsd"""
+        """Assert that duplicate portfolio user roles do not throw errors"""
         portfolio1 = Portfolio.objects.create(organization_name="Hotel California", creator=self.user2)
         UserPortfolioPermission.objects.create(
             user=self.user1, portfolio=portfolio1, roles=[UserPortfolioRoleChoices.ORGANIZATION_ADMIN]
@@ -3574,7 +3622,7 @@ class TestTransferUser(WebTest):
         with self.assertRaises(User.DoesNotExist):
             self.user2.refresh_from_db()
 
-    @less_console_noise_decorator
+    # @less_console_noise_decorator
     def test_transfer_user_throws_transfer_and_delete_success_messages(self):
         """Test that success messages for data transfer and user deletion are displayed."""
         # Ensure the setup for VerifiedByStaff
@@ -3592,11 +3640,13 @@ class TestTransferUser(WebTest):
 
             self.assertContains(after_submit, "<h1>Change user</h1>")
 
+            print(mock_success_message.call_args_list)
+
             mock_success_message.assert_any_call(
                 ANY,
                 (
                     "Data transferred successfully for the following objects: ['Changed requestor "
-                    + 'from "Furiosa Jabassa " to "Max Rokatanski " on immortan.joe@citadel.com\']'
+                    + "from Furiosa Jabassa  to Max Rokatanski  on immortan.joe@citadel.com']"
                 ),
             )
 
@@ -3606,7 +3656,7 @@ class TestTransferUser(WebTest):
     def test_transfer_user_throws_error_message(self):
         """Test that an error message is thrown if the transfer fails."""
         with patch(
-            "registrar.views.TransferUserView.transfer_user_fields_and_log", side_effect=Exception("Simulated Error")
+            "registrar.views.TransferUserView.transfer_related_fields_and_log", side_effect=Exception("Simulated Error")
         ):
             with patch("django.contrib.messages.error") as mock_error:
                 # Access the transfer user page
diff --git a/src/registrar/tests/test_email_invitations.py b/src/registrar/tests/test_email_invitations.py
new file mode 100644
index 000000000..87384d3be
--- /dev/null
+++ b/src/registrar/tests/test_email_invitations.py
@@ -0,0 +1,311 @@
+import unittest
+from unittest.mock import patch, MagicMock
+from datetime import date
+from registrar.utility.email import EmailSendingError
+from registrar.utility.email_invitations import send_domain_invitation_email
+
+from api.tests.common import less_console_noise_decorator
+
+
+class DomainInvitationEmail(unittest.TestCase):
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.send_templated_email")
+    @patch("registrar.utility.email_invitations.UserDomainRole.objects.filter")
+    @patch("registrar.utility.email_invitations.validate_invitation")
+    @patch("registrar.utility.email_invitations.get_requestor_email")
+    @patch("registrar.utility.email_invitations.send_invitation_email")
+    @patch("registrar.utility.email_invitations.normalize_domains")
+    def test_send_domain_invitation_email(
+        self,
+        mock_normalize_domains,
+        mock_send_invitation_email,
+        mock_get_requestor_email,
+        mock_validate_invitation,
+        mock_user_domain_role_filter,
+        mock_send_templated_email,
+    ):
+        """Test sending domain invitation email for one domain.
+        Should also send emails to manager of that domain.
+        """
+        # Setup
+        mock_domain = MagicMock(name="domain1")
+        mock_domain.name = "example.com"
+        mock_normalize_domains.return_value = [mock_domain]
+
+        mock_requestor = MagicMock()
+        mock_requestor_email = "requestor@example.com"
+        mock_get_requestor_email.return_value = mock_requestor_email
+
+        mock_user1 = MagicMock()
+        mock_user1.email = "manager1@example.com"
+
+        mock_user_domain_role_filter.return_value = [MagicMock(user=mock_user1)]
+
+        email = "invitee@example.com"
+        is_member_of_different_org = False
+
+        # Call the function
+        send_domain_invitation_email(
+            email=email,
+            requestor=mock_requestor,
+            domains=mock_domain,
+            is_member_of_different_org=is_member_of_different_org,
+        )
+
+        # Assertions
+        mock_normalize_domains.assert_called_once_with(mock_domain)
+        mock_get_requestor_email.assert_called_once_with(mock_requestor, [mock_domain])
+        mock_validate_invitation.assert_called_once_with(
+            email, [mock_domain], mock_requestor, is_member_of_different_org
+        )
+        mock_send_invitation_email.assert_called_once_with(email, mock_requestor_email, [mock_domain], None)
+        mock_user_domain_role_filter.assert_called_once_with(domain=mock_domain)
+        mock_send_templated_email.assert_called_once_with(
+            "emails/domain_manager_notification.txt",
+            "emails/domain_manager_notification_subject.txt",
+            to_address=mock_user1.email,
+            context={
+                "domain": mock_domain,
+                "requestor_email": mock_requestor_email,
+                "invited_email_address": email,
+                "domain_manager": mock_user1,
+                "date": date.today(),
+            },
+        )
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.send_templated_email")
+    @patch("registrar.utility.email_invitations.UserDomainRole.objects.filter")
+    @patch("registrar.utility.email_invitations.validate_invitation")
+    @patch("registrar.utility.email_invitations.get_requestor_email")
+    @patch("registrar.utility.email_invitations.send_invitation_email")
+    @patch("registrar.utility.email_invitations.normalize_domains")
+    def test_send_domain_invitation_email_multiple_domains(
+        self,
+        mock_normalize_domains,
+        mock_send_invitation_email,
+        mock_get_requestor_email,
+        mock_validate_invitation,
+        mock_user_domain_role_filter,
+        mock_send_templated_email,
+    ):
+        """Test sending domain invitation email for multiple domains.
+        Should also send emails to managers of each domain.
+        """
+        # Setup
+        # Create multiple mock domains
+        mock_domain1 = MagicMock(name="domain1")
+        mock_domain1.name = "example.com"
+        mock_domain2 = MagicMock(name="domain2")
+        mock_domain2.name = "example.org"
+
+        mock_normalize_domains.return_value = [mock_domain1, mock_domain2]
+
+        mock_requestor = MagicMock()
+        mock_requestor_email = "requestor@example.com"
+        mock_get_requestor_email.return_value = mock_requestor_email
+
+        mock_user1 = MagicMock()
+        mock_user1.email = "manager1@example.com"
+        mock_user2 = MagicMock()
+        mock_user2.email = "manager2@example.com"
+
+        # Configure domain roles for each domain
+        def filter_side_effect(domain):
+            if domain == mock_domain1:
+                return [MagicMock(user=mock_user1)]
+            elif domain == mock_domain2:
+                return [MagicMock(user=mock_user2)]
+            return []
+
+        mock_user_domain_role_filter.side_effect = filter_side_effect
+
+        email = "invitee@example.com"
+        is_member_of_different_org = False
+
+        # Call the function
+        send_domain_invitation_email(
+            email=email,
+            requestor=mock_requestor,
+            domains=[mock_domain1, mock_domain2],
+            is_member_of_different_org=is_member_of_different_org,
+        )
+
+        # Assertions
+        mock_normalize_domains.assert_called_once_with([mock_domain1, mock_domain2])
+        mock_get_requestor_email.assert_called_once_with(mock_requestor, [mock_domain1, mock_domain2])
+        mock_validate_invitation.assert_called_once_with(
+            email, [mock_domain1, mock_domain2], mock_requestor, is_member_of_different_org
+        )
+        mock_send_invitation_email.assert_called_once_with(
+            email, mock_requestor_email, [mock_domain1, mock_domain2], None
+        )
+
+        # Check that domain manager emails were sent for both domains
+        mock_user_domain_role_filter.assert_any_call(domain=mock_domain1)
+        mock_user_domain_role_filter.assert_any_call(domain=mock_domain2)
+
+        mock_send_templated_email.assert_any_call(
+            "emails/domain_manager_notification.txt",
+            "emails/domain_manager_notification_subject.txt",
+            to_address=mock_user1.email,
+            context={
+                "domain": mock_domain1,
+                "requestor_email": mock_requestor_email,
+                "invited_email_address": email,
+                "domain_manager": mock_user1,
+                "date": date.today(),
+            },
+        )
+        mock_send_templated_email.assert_any_call(
+            "emails/domain_manager_notification.txt",
+            "emails/domain_manager_notification_subject.txt",
+            to_address=mock_user2.email,
+            context={
+                "domain": mock_domain2,
+                "requestor_email": mock_requestor_email,
+                "invited_email_address": email,
+                "domain_manager": mock_user2,
+                "date": date.today(),
+            },
+        )
+
+        # Verify the total number of calls to send_templated_email
+        self.assertEqual(mock_send_templated_email.call_count, 2)
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.validate_invitation")
+    def test_send_domain_invitation_email_raises_invite_validation_exception(self, mock_validate_invitation):
+        """Test sending domain invitation email for one domain and assert exception
+        when invite validation fails.
+        """
+        # Setup
+        mock_validate_invitation.side_effect = ValueError("Validation failed")
+        email = "invitee@example.com"
+        requestor = MagicMock()
+        domain = MagicMock()
+
+        # Call and assert exception
+        with self.assertRaises(ValueError) as context:
+            send_domain_invitation_email(email, requestor, domain, is_member_of_different_org=False)
+
+        self.assertEqual(str(context.exception), "Validation failed")
+        mock_validate_invitation.assert_called_once()
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.get_requestor_email")
+    def test_send_domain_invitation_email_raises_get_requestor_email_exception(self, mock_get_requestor_email):
+        """Test sending domain invitation email for one domain and assert exception
+        when get_requestor_email fails.
+        """
+        # Setup
+        mock_get_requestor_email.side_effect = ValueError("Validation failed")
+        email = "invitee@example.com"
+        requestor = MagicMock()
+        domain = MagicMock()
+
+        # Call and assert exception
+        with self.assertRaises(ValueError) as context:
+            send_domain_invitation_email(email, requestor, domain, is_member_of_different_org=False)
+
+        self.assertEqual(str(context.exception), "Validation failed")
+        mock_get_requestor_email.assert_called_once()
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.validate_invitation")
+    @patch("registrar.utility.email_invitations.get_requestor_email")
+    @patch("registrar.utility.email_invitations.send_invitation_email")
+    @patch("registrar.utility.email_invitations.normalize_domains")
+    def test_send_domain_invitation_email_raises_sending_email_exception(
+        self,
+        mock_normalize_domains,
+        mock_send_invitation_email,
+        mock_get_requestor_email,
+        mock_validate_invitation,
+    ):
+        """Test sending domain invitation email for one domain and assert exception
+        when send_invitation_email fails.
+        """
+        # Setup
+        mock_domain = MagicMock(name="domain1")
+        mock_domain.name = "example.com"
+        mock_normalize_domains.return_value = [mock_domain]
+
+        mock_requestor = MagicMock()
+        mock_requestor_email = "requestor@example.com"
+        mock_get_requestor_email.return_value = mock_requestor_email
+
+        mock_user1 = MagicMock()
+        mock_user1.email = "manager1@example.com"
+
+        email = "invitee@example.com"
+        is_member_of_different_org = False
+
+        mock_send_invitation_email.side_effect = EmailSendingError("Error sending email")
+
+        # Call and assert exception
+        with self.assertRaises(EmailSendingError) as context:
+            send_domain_invitation_email(
+                email=email,
+                requestor=mock_requestor,
+                domains=mock_domain,
+                is_member_of_different_org=is_member_of_different_org,
+            )
+
+        # Assertions
+        mock_normalize_domains.assert_called_once_with(mock_domain)
+        mock_get_requestor_email.assert_called_once_with(mock_requestor, [mock_domain])
+        mock_validate_invitation.assert_called_once_with(
+            email, [mock_domain], mock_requestor, is_member_of_different_org
+        )
+        self.assertEqual(str(context.exception), "Error sending email")
+
+    @less_console_noise_decorator
+    @patch("registrar.utility.email_invitations.send_emails_to_domain_managers")
+    @patch("registrar.utility.email_invitations.validate_invitation")
+    @patch("registrar.utility.email_invitations.get_requestor_email")
+    @patch("registrar.utility.email_invitations.send_invitation_email")
+    @patch("registrar.utility.email_invitations.normalize_domains")
+    def test_send_domain_invitation_email_manager_emails_send_mail_exception(
+        self,
+        mock_normalize_domains,
+        mock_send_invitation_email,
+        mock_get_requestor_email,
+        mock_validate_invitation,
+        mock_send_domain_manager_emails,
+    ):
+        """Test sending domain invitation email for one domain and assert exception
+        when send_emails_to_domain_managers fails.
+        """
+        # Setup
+        mock_domain = MagicMock(name="domain1")
+        mock_domain.name = "example.com"
+        mock_normalize_domains.return_value = [mock_domain]
+
+        mock_requestor = MagicMock()
+        mock_requestor_email = "requestor@example.com"
+        mock_get_requestor_email.return_value = mock_requestor_email
+
+        email = "invitee@example.com"
+        is_member_of_different_org = False
+
+        mock_send_domain_manager_emails.side_effect = EmailSendingError("Error sending email")
+
+        # Call and assert exception
+        with self.assertRaises(EmailSendingError) as context:
+            send_domain_invitation_email(
+                email=email,
+                requestor=mock_requestor,
+                domains=mock_domain,
+                is_member_of_different_org=is_member_of_different_org,
+            )
+
+        # Assertions
+        mock_normalize_domains.assert_called_once_with(mock_domain)
+        mock_get_requestor_email.assert_called_once_with(mock_requestor, [mock_domain])
+        mock_validate_invitation.assert_called_once_with(
+            email, [mock_domain], mock_requestor, is_member_of_different_org
+        )
+        mock_send_invitation_email.assert_called_once_with(email, mock_requestor_email, [mock_domain], None)
+        self.assertEqual(str(context.exception), "Error sending email")
diff --git a/src/registrar/tests/test_management_scripts.py b/src/registrar/tests/test_management_scripts.py
index 655068493..536d1e760 100644
--- a/src/registrar/tests/test_management_scripts.py
+++ b/src/registrar/tests/test_management_scripts.py
@@ -2101,6 +2101,10 @@ class TestPatchSuborganizations(MockDbForIndividualTests):
         1. Fewest spaces
         2. Most leading capitals
         """
+        # Delete any other suborganizations defined in the initial test dataset
+        DomainRequest.objects.all().delete()
+        Suborganization.objects.all().delete()
+
         Suborganization.objects.create(name="Test Organization ", portfolio=self.portfolio_1)
         Suborganization.objects.create(name="test organization", portfolio=self.portfolio_1)
         Suborganization.objects.create(name="Test Organization", portfolio=self.portfolio_1)
@@ -2114,6 +2118,10 @@ class TestPatchSuborganizations(MockDbForIndividualTests):
     @less_console_noise_decorator
     def test_hardcoded_record(self):
         """Tests that our hardcoded records update as we expect them to"""
+        # Delete any other suborganizations defined in the initial test dataset
+        DomainRequest.objects.all().delete()
+        Suborganization.objects.all().delete()
+
         # Create orgs with old and new name formats
         old_name = "USDA/OC"
         new_name = "USDA, Office of Communications"
@@ -2123,7 +2131,7 @@ class TestPatchSuborganizations(MockDbForIndividualTests):
 
         self.run_patch_suborganizations()
 
-        # Verify only the new one remains
+        # Verify only the new one of the two remains
         self.assertEqual(Suborganization.objects.count(), 1)
         remaining = Suborganization.objects.first()
         self.assertEqual(remaining.name, new_name)
diff --git a/src/registrar/tests/test_models_domain.py b/src/registrar/tests/test_models_domain.py
index 15a88a608..083725a55 100644
--- a/src/registrar/tests/test_models_domain.py
+++ b/src/registrar/tests/test_models_domain.py
@@ -349,6 +349,70 @@ class TestDomainCache(MockEppLib):
 class TestDomainCreation(MockEppLib):
     """Rule: An approved domain request must result in a domain"""
 
+    @less_console_noise_decorator
+    def test_get_or_create_public_contact_race_condition(self):
+        """
+        Scenario: Two processes try to create the same security contact simultaneously
+            Given a domain in UNKNOWN state
+            When a race condition occurs during contact creation
+            Then no IntegrityError is raised
+            And only one security contact exists in database
+            And the correct public contact is returned
+
+        CONTEXT: We ran into an intermittent but somewhat rare issue where IntegrityError
+        was raised when creating PublicContact.
+        Per our logs, this seemed to appear during periods of high app activity.
+        """
+        domain, _ = Domain.objects.get_or_create(name="defaultsecurity.gov")
+
+        self.first_call = True
+
+        def mock_filter(*args, **kwargs):
+            """Simulates a race condition by creating a
+            duplicate contact between the first filter and save.
+            """
+            # Return an empty queryset for the first call. Otherwise just proceed as normal.
+            if self.first_call:
+                self.first_call = False
+                duplicate = PublicContact(
+                    domain=domain,
+                    contact_type=PublicContact.ContactTypeChoices.SECURITY,
+                    registry_id="defaultSec",
+                    email="dotgov@cisa.dhs.gov",
+                    name="Registry Customer Service",
+                )
+                duplicate.save(skip_epp_save=True)
+                return PublicContact.objects.none()
+
+            return PublicContact.objects.filter(*args, **kwargs)
+
+        with patch.object(PublicContact.objects, "filter", side_effect=mock_filter):
+            try:
+                public_contact = PublicContact(
+                    domain=domain,
+                    contact_type=PublicContact.ContactTypeChoices.SECURITY,
+                    registry_id="defaultSec",
+                    email="dotgov@cisa.dhs.gov",
+                    name="Registry Customer Service",
+                )
+                returned_public_contact = domain._get_or_create_public_contact(public_contact)
+            except IntegrityError:
+                self.fail(
+                    "IntegrityError was raised during contact creation due to a race condition. "
+                    "This indicates that concurrent contact creation is not working in some cases. "
+                    "The error occurs when two processes try to create the same contact simultaneously. "
+                    "Expected behavior: gracefully handle duplicate creation and return existing contact."
+                )
+
+        # Verify that only one contact exists and its correctness
+        security_contacts = PublicContact.objects.filter(
+            domain=domain, contact_type=PublicContact.ContactTypeChoices.SECURITY
+        )
+        self.assertEqual(security_contacts.count(), 1)
+        self.assertEqual(returned_public_contact, security_contacts.get())
+        self.assertEqual(returned_public_contact.registry_id, "defaultSec")
+        self.assertEqual(returned_public_contact.email, "dotgov@cisa.dhs.gov")
+
     @boto3_mocking.patching
     def test_approved_domain_request_creates_domain_locally(self):
         """
diff --git a/src/registrar/tests/test_reports.py b/src/registrar/tests/test_reports.py
index b11500ea9..9d410e430 100644
--- a/src/registrar/tests/test_reports.py
+++ b/src/registrar/tests/test_reports.py
@@ -729,6 +729,7 @@ class ExportDataTest(MockDbForIndividualTests, MockEppLib):
             # "Submitted at",
             "Status",
             "Domain type",
+            "Portfolio",
             "Federal type",
             "Federal agency",
             "Organization name",
@@ -736,6 +737,10 @@ class ExportDataTest(MockDbForIndividualTests, MockEppLib):
             "City",
             "State/territory",
             "Region",
+            "Suborganization",
+            "Requested suborg",
+            "Suborg city",
+            "Suborg state/territory",
             "Creator first name",
             "Creator last name",
             "Creator email",
@@ -765,28 +770,30 @@ class ExportDataTest(MockDbForIndividualTests, MockEppLib):
 
             expected_content = (
                 # Header
-                "Domain request,Status,Domain type,Federal type,Federal agency,Organization name,Election office,"
-                "City,State/territory,Region,Creator first name,Creator last name,Creator email,"
+                "Domain request,Status,Domain type,Portfolio,Federal type,Federal agency,Organization name,"
+                "Election office,City,State/territory,Region,Suborganization,Requested suborg,Suborg city,"
+                "Suborg state/territory,Creator first name,Creator last name,Creator email,"
                 "Creator approved domains count,Creator active requests count,Alternative domains,SO first name,"
                 "SO last name,SO email,SO title/role,Request purpose,Request additional details,Other contacts,"
                 "CISA regional representative,Current websites,Investigator\n"
                 # Content
-                "city5.gov,Approved,Federal,Executive,,Testorg,N/A,,NY,2,,,,1,0,city1.gov,Testy,Tester,testy@town.com,"
-                "Chief Tester,Purpose of the site,There is more,Testy Tester testy2@town.com,,city.com,\n"
-                "city2.gov,In review,Federal,Executive,Portfolio 1 Federal Agency,,N/A,,NY,2,,,,0,1,city1.gov,,,,,"
-                "Purpose of the site,There is more,Testy Tester testy2@town.com,,city.com,\n"
-                "city3.gov,Submitted,Federal,Executive,Portfolio 1 Federal Agency,,N/A,,NY,2,,,,0,1,"
+                "city5.gov,Approved,Federal,No,Executive,,Testorg,N/A,,NY,2,requested_suborg,SanFran,CA,,,,,1,0,"
+                "city1.gov,Testy,Tester,testy@town.com,Chief Tester,Purpose of the site,There is more,"
+                "Testy Tester testy2@town.com,,city.com,\n"
+                "city2.gov,In review,Federal,Yes,Executive,Portfolio 1 Federal Agency,,N/A,,,2,SubOrg 1,,,,,,,0,"
+                "1,city1.gov,,,,,Purpose of the site,There is more,Testy Tester testy2@town.com,,city.com,\n"
+                "city3.gov,Submitted,Federal,Yes,Executive,Portfolio 1 Federal Agency,,N/A,,,2,,,,,,,,0,1,"
                 '"cheeseville.gov, city1.gov, igorville.gov",,,,,Purpose of the site,CISA-first-name CISA-last-name | '
                 'There is more,"Meow Tester24 te2@town.com, Testy1232 Tester24 te2@town.com, '
                 'Testy Tester testy2@town.com",'
                 'test@igorville.com,"city.com, https://www.example2.com, https://www.example.com",\n'
-                "city4.gov,Submitted,City,Executive,,Testorg,Yes,,NY,2,,,,0,1,city1.gov,Testy,"
+                "city4.gov,Submitted,City,No,Executive,,Testorg,Yes,,NY,2,,,,,,,,0,1,city1.gov,Testy,"
                 "Tester,testy@town.com,"
                 "Chief Tester,Purpose of the site,CISA-first-name CISA-last-name | There is more,"
                 "Testy Tester testy2@town.com,"
                 "cisaRep@igorville.gov,city.com,\n"
-                "city6.gov,Submitted,Federal,Executive,Portfolio 1 Federal Agency,,N/A,,NY,2,,,,0,1,city1.gov,,,,,"
-                "Purpose of the site,CISA-first-name CISA-last-name | There is more,Testy Tester testy2@town.com,"
+                "city6.gov,Submitted,Federal,Yes,Executive,Portfolio 1 Federal Agency,,N/A,,,2,,,,,,,,0,1,city1.gov,"
+                ",,,,Purpose of the site,CISA-first-name CISA-last-name | There is more,Testy Tester testy2@town.com,"
                 "cisaRep@igorville.gov,city.com,\n"
             )
 
diff --git a/src/registrar/tests/test_views_domain.py b/src/registrar/tests/test_views_domain.py
index f13490312..45758e502 100644
--- a/src/registrar/tests/test_views_domain.py
+++ b/src/registrar/tests/test_views_domain.py
@@ -9,7 +9,7 @@ from registrar.utility.email import EmailSendingError
 from waffle.testutils import override_flag
 from api.tests.common import less_console_noise_decorator
 from registrar.models.utility.portfolio_helper import UserPortfolioPermissionChoices, UserPortfolioRoleChoices
-from .common import MockEppLib, MockSESClient, create_user  # type: ignore
+from .common import MockEppLib, create_user  # type: ignore
 from django_webtest import WebTest  # type: ignore
 import boto3_mocking  # type: ignore
 
@@ -750,11 +750,12 @@ class TestDomainManagers(TestDomainOverview):
         response = self.client.get(reverse("domain-users-add", kwargs={"pk": self.domain.id}))
         self.assertContains(response, "Add a domain manager")
 
-    @boto3_mocking.patching
     @less_console_noise_decorator
-    def test_domain_user_add_form(self):
+    @patch("registrar.views.domain.send_domain_invitation_email")
+    def test_domain_user_add_form(self, mock_send_domain_email):
         """Adding an existing user works."""
         get_user_model().objects.get_or_create(email="mayor@igorville.gov")
+        user = User.objects.filter(email="mayor@igorville.gov").first()
         add_page = self.app.get(reverse("domain-users-add", kwargs={"pk": self.domain.id}))
         session_id = self.app.cookies[settings.SESSION_COOKIE_NAME]
 
@@ -762,10 +763,15 @@ class TestDomainManagers(TestDomainOverview):
 
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
 
-        mock_client = MockSESClient()
-        with boto3_mocking.clients.handler_for("sesv2", mock_client):
-            with less_console_noise():
-                success_result = add_page.form.submit()
+        success_result = add_page.form.submit()
+
+        mock_send_domain_email.assert_called_once_with(
+            email="mayor@igorville.gov",
+            requestor=self.user,
+            domains=self.domain,
+            is_member_of_different_org=None,
+            requested_user=user,
+        )
 
         self.assertEqual(success_result.status_code, 302)
         self.assertEqual(
@@ -974,13 +980,13 @@ class TestDomainManagers(TestDomainOverview):
         success_page = success_result.follow()
         self.assertContains(success_page, "Failed to send email.")
 
-    @boto3_mocking.patching
     @less_console_noise_decorator
-    def test_domain_invitation_created(self):
+    @patch("registrar.views.domain.send_domain_invitation_email")
+    def test_domain_invitation_created(self, mock_send_domain_email):
         """Add user on a nonexistent email creates an invitation.
 
         Adding a non-existent user sends an email as a side-effect, so mock
-        out the boto3 SES email sending here.
+        out send_domain_invitation_email here.
         """
         # make sure there is no user with this email
         email_address = "mayor@igorville.gov"
@@ -993,10 +999,11 @@ class TestDomainManagers(TestDomainOverview):
         add_page.form["email"] = email_address
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
 
-        mock_client = MockSESClient()
-        with boto3_mocking.clients.handler_for("sesv2", mock_client):
-            with less_console_noise():
-                success_result = add_page.form.submit()
+        success_result = add_page.form.submit()
+
+        mock_send_domain_email.assert_called_once_with(
+            email="mayor@igorville.gov", requestor=self.user, domains=self.domain, is_member_of_different_org=None
+        )
 
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
         success_page = success_result.follow()
@@ -1005,13 +1012,13 @@ class TestDomainManagers(TestDomainOverview):
         self.assertContains(success_page, "Cancel")  # link to cancel invitation
         self.assertTrue(DomainInvitation.objects.filter(email=email_address).exists())
 
-    @boto3_mocking.patching
     @less_console_noise_decorator
-    def test_domain_invitation_created_for_caps_email(self):
+    @patch("registrar.views.domain.send_domain_invitation_email")
+    def test_domain_invitation_created_for_caps_email(self, mock_send_domain_email):
         """Add user on a nonexistent email with CAPS creates an invitation to lowercase email.
 
         Adding a non-existent user sends an email as a side-effect, so mock
-        out the boto3 SES email sending here.
+        out send_domain_invitation_email here.
         """
         # make sure there is no user with this email
         email_address = "mayor@igorville.gov"
@@ -1025,9 +1032,11 @@ class TestDomainManagers(TestDomainOverview):
         add_page.form["email"] = caps_email_address
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
 
-        mock_client = MockSESClient()
-        with boto3_mocking.clients.handler_for("sesv2", mock_client):
-            success_result = add_page.form.submit()
+        success_result = add_page.form.submit()
+
+        mock_send_domain_email.assert_called_once_with(
+            email="mayor@igorville.gov", requestor=self.user, domains=self.domain, is_member_of_different_org=None
+        )
 
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
         success_page = success_result.follow()
diff --git a/src/registrar/tests/test_views_portfolio.py b/src/registrar/tests/test_views_portfolio.py
index 78a4dae82..69502d683 100644
--- a/src/registrar/tests/test_views_portfolio.py
+++ b/src/registrar/tests/test_views_portfolio.py
@@ -2879,7 +2879,7 @@ class TestRequestingEntity(WebTest):
 
         form["portfolio_requesting_entity-requesting_entity_is_suborganization"] = True
         form["portfolio_requesting_entity-is_requesting_new_suborganization"] = True
-        form["portfolio_requesting_entity-sub_organization"] = ""
+        form["portfolio_requesting_entity-sub_organization"] = "other"
 
         form["portfolio_requesting_entity-requested_suborganization"] = "moon"
         form["portfolio_requesting_entity-suborganization_city"] = "kepler"
@@ -2942,18 +2942,34 @@ class TestRequestingEntity(WebTest):
         session_id = self.app.cookies[settings.SESSION_COOKIE_NAME]
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
 
+        # For 2 the tests below, it is required to submit a form without submitting a value
+        # for the select/combobox. WebTest will not do this; by default, WebTest will submit
+        # the first choice in a select. So, need to manipulate the form to remove the
+        # particular select/combobox that will not be submitted, and then post the form.
+        form_action = f"/request/{domain_request.pk}/portfolio_requesting_entity/"
+
         # Test missing suborganization selection
         form["portfolio_requesting_entity-requesting_entity_is_suborganization"] = True
-        form["portfolio_requesting_entity-sub_organization"] = ""
-
-        response = form.submit()
+        form["portfolio_requesting_entity-is_requesting_new_suborganization"] = False
+        # remove sub_organization from the form submission
+        form_data = form.submit_fields()
+        form_data = [(key, value) for key, value in form_data if key != "portfolio_requesting_entity-sub_organization"]
+        response = self.app.post(form_action, dict(form_data))
         self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
         self.assertContains(response, "Suborganization is required.", status_code=200)
 
         # Test missing custom suborganization details
+        form["portfolio_requesting_entity-requesting_entity_is_suborganization"] = True
         form["portfolio_requesting_entity-is_requesting_new_suborganization"] = True
-        response = form.submit()
-        self.app.set_cookie(settings.SESSION_COOKIE_NAME, session_id)
+        form["portfolio_requesting_entity-sub_organization"] = "other"
+        # remove suborganization_state_territory from the form submission
+        form_data = form.submit_fields()
+        form_data = [
+            (key, value)
+            for key, value in form_data
+            if key != "portfolio_requesting_entity-suborganization_state_territory"
+        ]
+        response = self.app.post(form_action, dict(form_data))
         self.assertContains(response, "Enter the name of your suborganization.", status_code=200)
         self.assertContains(response, "Enter the city where your suborganization is located.", status_code=200)
         self.assertContains(
diff --git a/src/registrar/utility/csv_export.py b/src/registrar/utility/csv_export.py
index 6e5773ebb..1bb53a7a3 100644
--- a/src/registrar/utility/csv_export.py
+++ b/src/registrar/utility/csv_export.py
@@ -1660,6 +1660,27 @@ class DomainRequestExport(BaseExport):
                 default=F("organization_name"),
                 output_field=CharField(),
             ),
+            "converted_city": Case(
+                # When portfolio is present, use its value instead
+                When(portfolio__isnull=False, then=F("portfolio__city")),
+                # Otherwise, return the natively assigned value
+                default=F("city"),
+                output_field=CharField(),
+            ),
+            "converted_state_territory": Case(
+                # When portfolio is present, use its value instead
+                When(portfolio__isnull=False, then=F("portfolio__state_territory")),
+                # Otherwise, return the natively assigned value
+                default=F("state_territory"),
+                output_field=CharField(),
+            ),
+            "converted_suborganization_name": Case(
+                # When sub_organization is present, use its name
+                When(sub_organization__isnull=False, then=F("sub_organization__name")),
+                # Otherwise, return empty string
+                default=Value(""),
+                output_field=CharField(),
+            ),
             "converted_so_email": Case(
                 # When portfolio is present, use its value instead
                 When(portfolio__isnull=False, then=F("portfolio__senior_official__email")),
@@ -1786,6 +1807,10 @@ class DomainRequestExport(BaseExport):
         status = model.get("status")
         status_display = DomainRequest.DomainRequestStatus.get_status_label(status) if status else None
 
+        # Handle the portfolio field. Display as a Yes/No
+        portfolio = model.get("portfolio")
+        portfolio_display = "Yes" if portfolio is not None else "No"
+
         # Handle the region field.
         state_territory = model.get("state_territory")
         region = get_region(state_territory) if state_territory else None
@@ -1819,6 +1844,7 @@ class DomainRequestExport(BaseExport):
             "Election office": human_readable_election_board,
             "Federal type": human_readable_federal_type,
             "Domain type": human_readable_org_type,
+            "Portfolio": portfolio_display,
             "Request additional details": additional_details,
             # Annotated fields - passed into the request dict.
             "Creator approved domains count": model.get("creator_approved_domains_count", 0),
@@ -1827,6 +1853,10 @@ class DomainRequestExport(BaseExport):
             "Other contacts": model.get("all_other_contacts"),
             "Current websites": model.get("all_current_websites"),
             # Untouched FK fields - passed into the request dict.
+            "Suborganization": model.get("converted_suborganization_name"),
+            "Requested suborg": model.get("requested_suborganization"),
+            "Suborg city": model.get("suborganization_city"),
+            "Suborg state/territory": model.get("suborganization_state_territory"),
             "Federal agency": model.get("converted_federal_agency"),
             "SO first name": model.get("converted_senior_official_first_name"),
             "SO last name": model.get("converted_senior_official_last_name"),
@@ -1838,8 +1868,8 @@ class DomainRequestExport(BaseExport):
             "Investigator": model.get("investigator__email"),
             # Untouched fields
             "Organization name": model.get("converted_organization_name"),
-            "City": model.get("city"),
-            "State/territory": model.get("state_territory"),
+            "City": model.get("converted_city"),
+            "State/territory": model.get("converted_state_territory"),
             "Request purpose": model.get("purpose"),
             "CISA regional representative": model.get("cisa_representative_email"),
             "Last submitted date": model.get("last_submitted_date"),
@@ -2006,6 +2036,7 @@ class DomainRequestDataFull(DomainRequestExport):
             "Last status update",
             "Status",
             "Domain type",
+            "Portfolio",
             "Federal type",
             "Federal agency",
             "Organization name",
@@ -2013,6 +2044,10 @@ class DomainRequestDataFull(DomainRequestExport):
             "City",
             "State/territory",
             "Region",
+            "Suborganization",
+            "Requested suborg",
+            "Suborg city",
+            "Suborg state/territory",
             "Creator first name",
             "Creator last name",
             "Creator email",
diff --git a/src/registrar/utility/db_helpers.py b/src/registrar/utility/db_helpers.py
new file mode 100644
index 000000000..5b7e0392c
--- /dev/null
+++ b/src/registrar/utility/db_helpers.py
@@ -0,0 +1,20 @@
+from contextlib import contextmanager
+from django.db import transaction, IntegrityError
+from psycopg2 import errorcodes
+
+
+@contextmanager
+def ignore_unique_violation():
+    """
+    Execute within an atomic transaction so that if a unique constraint violation occurs,
+    the individual transaction is rolled back without invalidating any larger transaction.
+    """
+    with transaction.atomic():
+        try:
+            yield
+        except IntegrityError as e:
+            if e.__cause__.pgcode == errorcodes.UNIQUE_VIOLATION:
+                # roll back to the savepoint, effectively ignoring this transaction
+                pass
+            else:
+                raise e
diff --git a/src/registrar/utility/email_invitations.py b/src/registrar/utility/email_invitations.py
index 48c796340..25e9db0f3 100644
--- a/src/registrar/utility/email_invitations.py
+++ b/src/registrar/utility/email_invitations.py
@@ -1,6 +1,6 @@
+from datetime import date
 from django.conf import settings
-from registrar.models import DomainInvitation
-from registrar.models.domain import Domain
+from registrar.models import Domain, DomainInvitation, UserDomainRole
 from registrar.utility.errors import (
     AlreadyDomainInvitedError,
     AlreadyDomainManagerError,
@@ -41,8 +41,47 @@ def send_domain_invitation_email(
 
     send_invitation_email(email, requestor_email, domains, requested_user)
 
+    # send emails to domain managers
+    for domain in domains:
+        send_emails_to_domain_managers(
+            email=email,
+            requestor_email=requestor_email,
+            domain=domain,
+            requested_user=requested_user,
+        )
 
-def normalize_domains(domains):
+
+def send_emails_to_domain_managers(email: str, requestor_email, domain: Domain, requested_user=None):
+    """
+    Notifies all domain managers of the provided domain of a change
+    Raises:
+        EmailSendingError
+    """
+    # Get each domain manager from list
+    user_domain_roles = UserDomainRole.objects.filter(domain=domain)
+    for user_domain_role in user_domain_roles:
+        # Send email to each domain manager
+        user = user_domain_role.user
+        try:
+            send_templated_email(
+                "emails/domain_manager_notification.txt",
+                "emails/domain_manager_notification_subject.txt",
+                to_address=user.email,
+                context={
+                    "domain": domain,
+                    "requestor_email": requestor_email,
+                    "invited_email_address": email,
+                    "domain_manager": user,
+                    "date": date.today(),
+                },
+            )
+        except EmailSendingError as err:
+            raise EmailSendingError(
+                f"Could not send email manager notification to {user.email} for domain: {domain.name}"
+            ) from err
+
+
+def normalize_domains(domains: Domain | list[Domain]) -> list[Domain]:
     """Ensures domains is always a list."""
     return [domains] if isinstance(domains, Domain) else domains
 
@@ -69,6 +108,8 @@ def validate_invitation(email, domains, requestor, is_member_of_different_org):
     for domain in domains:
         validate_existing_invitation(email, domain)
 
+        # NOTE: should we also be validating against existing user_domain_roles
+
 
 def check_outside_org_membership(email, requestor, is_member_of_different_org):
     """Raise an error if the email belongs to a different organization."""
diff --git a/src/registrar/views/transfer_user.py b/src/registrar/views/transfer_user.py
index 69a0f4997..f574b76d9 100644
--- a/src/registrar/views/transfer_user.py
+++ b/src/registrar/views/transfer_user.py
@@ -1,19 +1,19 @@
 import logging
+from django.db import transaction
+from django.db.models import ForeignKey, OneToOneField, ManyToManyField, ManyToOneRel, ManyToManyRel, OneToOneRel
 
 from django.shortcuts import render, get_object_or_404, redirect
 from django.views import View
 from registrar.models.domain import Domain
-from registrar.models.domain_information import DomainInformation
 from registrar.models.domain_request import DomainRequest
-from registrar.models.portfolio import Portfolio
 from registrar.models.user import User
 from django.contrib.admin import site
 from django.contrib import messages
 
 from registrar.models.user_domain_role import UserDomainRole
 from registrar.models.user_portfolio_permission import UserPortfolioPermission
-from registrar.models.verified_by_staff import VerifiedByStaff
-from typing import Any, List
+
+from registrar.utility.db_helpers import ignore_unique_violation
 
 logger = logging.getLogger(__name__)
 
@@ -21,22 +21,8 @@ logger = logging.getLogger(__name__)
 class TransferUserView(View):
     """Transfer user methods that set up the transfer_user template and handle the forms on it."""
 
-    JOINS = [
-        (DomainRequest, "creator"),
-        (DomainInformation, "creator"),
-        (Portfolio, "creator"),
-        (DomainRequest, "investigator"),
-        (UserDomainRole, "user"),
-        (VerifiedByStaff, "requestor"),
-        (UserPortfolioPermission, "user"),
-    ]
-
-    # Future-proofing in case joined fields get added on the user model side
-    # This was tested in the first portfolio model iteration and works
-    USER_FIELDS: List[Any] = []
-
     def get(self, request, user_id):
-        """current_user referes to the 'source' user where the button that redirects to this view was clicked.
+        """current_user refers to the 'source' user where the button that redirects to this view was clicked.
         other_users exclude current_user and populate a dropdown, selected_user is the selection in the dropdown.
 
         This also querries the relevant domains and domain requests, and the admin context needed for the sidenav."""
@@ -70,86 +56,122 @@ class TransferUserView(View):
         return render(request, "admin/transfer_user.html", context)
 
     def post(self, request, user_id):
-        """This handles the transfer from selected_user to current_user then deletes selected_user.
-
-        NOTE: We have a ticket to refactor this into a more solid lookup for related fields in #2645"""
-
+        """This handles the transfer from selected_user to current_user then deletes selected_user."""
         current_user = get_object_or_404(User, pk=user_id)
         selected_user_id = request.POST.get("selected_user")
         selected_user = get_object_or_404(User, pk=selected_user_id)
 
         try:
-            change_logs = []
+            # Make this atomic so that we don't get any partial transfers
+            with transaction.atomic():
+                change_logs = []
 
-            # Transfer specific fields
-            self.transfer_user_fields_and_log(selected_user, current_user, change_logs)
+                # Dynamically handle related fields
+                self.transfer_related_fields_and_log(selected_user, current_user, change_logs)
 
-            # Perform the updates and log the changes
-            for model_class, field_name in self.JOINS:
-                self.update_joins_and_log(model_class, field_name, selected_user, current_user, change_logs)
-
-            # Success message if any related objects were updated
-            if change_logs:
-                success_message = f"Data transferred successfully for the following objects: {change_logs}"
-                messages.success(request, success_message)
-
-            selected_user.delete()
-            messages.success(request, f"Deleted {selected_user} {selected_user.username}")
+                # Success message if any related objects were updated
+                if change_logs:
+                    success_message = f"Data transferred successfully for the following objects: {change_logs}"
+                    messages.success(request, success_message)
 
+                selected_user.delete()
+                messages.success(request, f"Deleted {selected_user} {selected_user.username}")
         except Exception as e:
             messages.error(request, f"An error occurred during the transfer: {e}")
+            logger.error(f"An error occurred during the transfer: {e}", exc_info=True)
 
         return redirect("admin:registrar_user_change", object_id=user_id)
 
-    @classmethod
-    def update_joins_and_log(cls, model_class, field_name, selected_user, current_user, change_logs):
+    def transfer_related_fields_and_log(self, selected_user, current_user, change_logs):
         """
-        Helper function to update the user join fields for a given model and log the changes.
+        Dynamically find all related fields to the User model and transfer them from selected_user to current_user.
+        Handles ForeignKey, OneToOneField, ManyToManyField, and ManyToOneRel relationships.
         """
+        user_model = User
 
-        filter_kwargs = {field_name: selected_user}
-        updated_objects = model_class.objects.filter(**filter_kwargs)
+        for related_field in user_model._meta.get_fields():
+            if related_field.is_relation:
+                # Field objects represent forward relationships
+                if isinstance(related_field, OneToOneField):
+                    self._handle_one_to_one(related_field, selected_user, current_user, change_logs)
+                elif isinstance(related_field, ManyToManyField):
+                    self._handle_many_to_many(related_field, selected_user, current_user, change_logs)
+                elif isinstance(related_field, ForeignKey):
+                    self._handle_foreign_key(related_field, selected_user, current_user, change_logs)
+                # Relationship objects represent reverse relationships
+                elif isinstance(related_field, ManyToOneRel):
+                    # ManyToOneRel is a reverse ForeignKey
+                    self._handle_foreign_key_reverse(related_field, selected_user, current_user, change_logs)
+                elif isinstance(related_field, OneToOneRel):
+                    self._handle_one_to_one_reverse(related_field, selected_user, current_user, change_logs)
+                elif isinstance(related_field, ManyToManyRel):
+                    self._handle_many_to_many_reverse(related_field, selected_user, current_user, change_logs)
+                else:
+                    logger.error(f"Unknown relationship type for field {related_field}")
+                    raise ValueError(f"Unknown relationship type for field {related_field}")
 
-        for obj in updated_objects:
-            # Check for duplicate UserDomainRole before updating
-            if model_class == UserDomainRole:
-                if model_class.objects.filter(user=current_user, domain=obj.domain).exists():
-                    continue  # Skip the update to avoid a duplicate
+    def _handle_foreign_key_reverse(self, related_field: ManyToOneRel, selected_user, current_user, change_logs):
+        # Handle reverse ForeignKey relationships
+        related_manager = getattr(selected_user, related_field.get_accessor_name(), None)
+        if related_manager and related_manager.exists():
+            for related_object in related_manager.all():
+                with ignore_unique_violation():
+                    setattr(related_object, related_field.field.name, current_user)
+                    related_object.save()
+                self.log_change(related_object, selected_user, current_user, related_field.field.name, change_logs)
 
-            if model_class == UserPortfolioPermission:
-                if model_class.objects.filter(user=current_user, portfolio=obj.portfolio).exists():
-                    continue  # Skip the update to avoid a duplicate
+    def _handle_foreign_key(self, related_field: ForeignKey, selected_user, current_user, change_logs):
+        # Handle ForeignKey relationships
+        related_object = getattr(selected_user, related_field.name, None)
+        if related_object:
+            setattr(current_user, related_field.name, related_object)
+            current_user.save()
+            self.log_change(related_object, selected_user, current_user, related_field.name, change_logs)
 
-            # Update the field on the object and save it
-            setattr(obj, field_name, current_user)
-            obj.save()
+    def _handle_one_to_one(self, related_field: OneToOneField, selected_user, current_user, change_logs):
+        # Handle OneToOne relationship
+        related_object = getattr(selected_user, related_field.name, None)
+        if related_object:
+            with ignore_unique_violation():
+                setattr(current_user, related_field.name, related_object)
+                current_user.save()
+            self.log_change(related_object, selected_user, current_user, related_field.name, change_logs)
 
-            # Log the change
-            cls.log_change(obj, field_name, selected_user, current_user, change_logs)
+    def _handle_many_to_many(self, related_field: ManyToManyField, selected_user, current_user, change_logs):
+        # Handle ManyToMany relationship
+        related_name = related_field.remote_field.name
+        related_manager = getattr(selected_user, related_name, None)
+        if related_manager and related_manager.exists():
+            for instance in related_manager.all():
+                with ignore_unique_violation():
+                    getattr(instance, related_name).remove(selected_user)
+                    getattr(instance, related_name).add(current_user)
+                self.log_change(instance, selected_user, current_user, related_name, change_logs)
+
+    def _handle_many_to_many_reverse(self, related_field: ManyToManyRel, selected_user, current_user, change_logs):
+        # Handle reverse relationship
+        related_name = related_field.field.name
+        related_manager = getattr(selected_user, related_name, None)
+        if related_manager and related_manager.exists():
+            for instance in related_manager.all():
+                with ignore_unique_violation():
+                    getattr(instance, related_name).remove(selected_user)
+                    getattr(instance, related_name).add(current_user)
+                self.log_change(instance, selected_user, current_user, related_name, change_logs)
+
+    def _handle_one_to_one_reverse(self, related_field: OneToOneRel, selected_user, current_user, change_logs):
+        # Handle reverse relationship
+        field_name = related_field.get_accessor_name()
+        related_instance = getattr(selected_user, field_name, None)
+        if related_instance:
+            setattr(related_instance, field_name, current_user)
+            related_instance.save()
+            self.log_change(related_instance, selected_user, current_user, field_name, change_logs)
 
     @classmethod
-    def transfer_user_fields_and_log(cls, selected_user, current_user, change_logs):
-        """
-        Transfers portfolio fields from the selected_user to the current_user.
-        Logs the changes for each transferred field.
-        """
-        for field in cls.USER_FIELDS:
-            field_value = getattr(selected_user, field, None)
-
-            if field_value:
-                setattr(current_user, field, field_value)
-                cls.log_change(current_user, field, field_value, field_value, change_logs)
-
-        current_user.save()
-
-    @classmethod
-    def log_change(cls, obj, field_name, field_value, new_value, change_logs):
-        """Logs the change for a specific field on an object"""
-        log_entry = f'Changed {field_name} from "{field_value}" to "{new_value}" on {obj}'
-
+    def log_change(cls, obj, selected_user, current_user, field_name, change_logs):
+        log_entry = f"Changed {field_name} from {selected_user} to {current_user} on {obj}"
         logger.info(log_entry)
-
-        # Collect the related object for the success message
         change_logs.append(log_entry)
 
     @classmethod