diff --git a/src/BusProNet/DataProcessor/BookingDataProcessor.php b/src/BusProNet/DataProcessor/BookingDataProcessor.php
index da207cc..76bb7b0 100644
--- a/src/BusProNet/DataProcessor/BookingDataProcessor.php
+++ b/src/BusProNet/DataProcessor/BookingDataProcessor.php
@@ -162,6 +162,8 @@ class BookingDataProcessor
                 $roomSelection->label = $room->label;
                 $roomSelection->price = $room->price;
                 $roomSelection->quantity = $bookingRoom->totalCount; // Actual quantity from booking XML (anzahl)
+                $roomSelection->capacity = $room->minPax ?? 1;
+                $roomSelection->maxQuantity = $bookingRoom->totalCount + ($room->available ?? 0);
                 $dto->roomSelections[] = $roomSelection;
             }
         }
diff --git a/src/BusProNet/DataProcessor/BookingPayloadBuilder.php b/src/BusProNet/DataProcessor/BookingPayloadBuilder.php
index 56991c9..85da2dd 100644
--- a/src/BusProNet/DataProcessor/BookingPayloadBuilder.php
+++ b/src/BusProNet/DataProcessor/BookingPayloadBuilder.php
@@ -172,7 +172,7 @@ class BookingPayloadBuilder
                 '@idverpflegung' => $room->boardId,
                 '@anreise' => $room->dateFrom ? $room->dateFrom->format('d.m.Y') : null,
                 '@abreise' => $room->dateTo ? $room->dateTo->format('d.m.Y') : null,
-                '@anzahl' => $room->totalCount,
+                '@anzahl' => count($uniqueMapping),
                 '@zuordnung' => implode(',', array_map(fn ($index) => $index + 1, $uniqueMapping)),
             ];
         }
@@ -456,21 +456,12 @@ class BookingPayloadBuilder
         $availableRooms = $bookingDto->travel->getAvailableRooms();
         $payload['ferienzielunterbringungen']['ferienzielunterbringung'] = [];
 
-        // Build room selection quantity lookup
-        $roomQuantities = [];
-        foreach ($bookingDto->roomSelections as $selection) {
-            if ($selection->quantity > 0) {
-                $roomQuantities[$selection->id] = $selection->quantity;
-            }
-        }
-
         foreach ($roomMap as $roomId => $participantIds) {
             $room = $availableRooms[$roomId] ?? null;
             if (null === $room) {
                 continue;
             }
 
-            $quantity = $roomQuantities[$roomId] ?? 1;
             $uniqueParticipantIds = array_unique($participantIds);
 
             $payload['ferienzielunterbringungen']['ferienzielunterbringung'][] = [
@@ -479,7 +470,7 @@ class BookingPayloadBuilder
                 '@idverpflegung' => $room->boardId,
                 '@anreise' => $bookingDto->travel->dateFrom->format('d.m.Y'),
                 '@abreise' => $bookingDto->travel->dateTo->format('d.m.Y'),
-                '@anzahl' => $quantity,
+                '@anzahl' => count($uniqueParticipantIds),
                 '@zuordnung' => implode(',', $uniqueParticipantIds),
             ];
         }
diff --git a/src/Form/Model/ParticipantEditDto.php b/src/Form/Model/ParticipantEditDto.php
index 96bcc32..30b6afc 100644
--- a/src/Form/Model/ParticipantEditDto.php
+++ b/src/Form/Model/ParticipantEditDto.php
@@ -132,6 +132,11 @@ class ParticipantEditDto
     #[Assert\Callback(groups: ['booking_create', 'booking_edit'])]
     public function validateEmailUniqueness(ExecutionContextInterface $context): void
     {
+        // Skip for internal agency bookings — staff use shared placeholder emails
+        if ($this->bookingContext->isInternalAgencyBooking()) {
+            return;
+        }
+
         // Skip validation for applicant (index 0) - applicant's email can be shared with dependents
         if (true === $this->participant->isApplicant()) {
             return;
diff --git a/src/Form/Service/Condition/AccommodationMutabilityCondition.php b/src/Form/Service/Condition/AccommodationMutabilityCondition.php
new file mode 100644
index 0000000..e5bb0fc
--- /dev/null
+++ b/src/Form/Service/Condition/AccommodationMutabilityCondition.php
@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Form\Service\Condition;
+
+use App\Form\Model\BookingDto;
+use App\Form\Service\Contract\FieldConditionInterface;
+
+/**
+ * Condition that checks if accommodation (room assignments) are mutable in the edit flow.
+ */
+class AccommodationMutabilityCondition implements FieldConditionInterface
+{
+    public function evaluate(BookingDto $bookingDto, int $participantIndex, array $formData): bool
+    {
+        return false === $bookingDto->travel->roomsMutable;
+    }
+
+    public function getDependentFields(): array
+    {
+        return [];
+    }
+
+    public function getDescription(): string
+    {
+        return 'Accommodation is not mutable (edit flow)';
+    }
+}
diff --git a/src/Form/Service/EditFieldStateProvider.php b/src/Form/Service/EditFieldStateProvider.php
index 6a94907..a2502a0 100644
--- a/src/Form/Service/EditFieldStateProvider.php
+++ b/src/Form/Service/EditFieldStateProvider.php
@@ -5,11 +5,10 @@ declare(strict_types=1);
 namespace App\Form\Service;
 
 use App\BusProNet\Utility\DirectionMapper;
-use App\Form\Model\BookingDto;
 use App\Form\Service\Abstract\AbstractFieldStateProvider;
+use App\Form\Service\Condition\AccommodationMutabilityCondition;
 use App\Form\Service\Condition\AdditionalServicesMutabilityCondition;
 use App\Form\Service\Condition\AgeRangeCondition;
-use App\Form\Service\Condition\BookingModeCondition;
 use App\Form\Service\Condition\CompositeCondition;
 use App\Form\Service\Condition\DateOfBirthProvidedCondition;
 use App\Form\Service\Condition\FieldValueCondition;
@@ -99,10 +98,10 @@ class EditFieldStateProvider extends AbstractFieldStateProvider
             'static_text' => $personalDataHiddenCondition,
         ];
 
-        // Room assignments are fixed in edit mode - always render as static text
-        // The assignedRoomId value passes through unchanged from the loaded booking data
+        // Room assignments are readonly when BPN indicates accommodation is not mutable
+        $accommodationMutabilityCondition = new AccommodationMutabilityCondition();
         $this->fieldStateConditions['assignedRoomId'] = [
-            'static_text' => new BookingModeCondition(BookingDto::MODE_EDIT),
+            'static_text' => $accommodationMutabilityCondition,
         ];
 
         // Show remarks room field only when room with code 'mbz' (single bed) is selected
diff --git a/src/Form/Service/ParticipantAssignedRoomFieldHandler.php b/src/Form/Service/ParticipantAssignedRoomFieldHandler.php
index 262b6be..6698531 100644
--- a/src/Form/Service/ParticipantAssignedRoomFieldHandler.php
+++ b/src/Form/Service/ParticipantAssignedRoomFieldHandler.php
@@ -122,7 +122,14 @@ class ParticipantAssignedRoomFieldHandler extends AbstractParticipantFieldHandle
         }
 
         // Calculate total capacity for this room type
-        $totalCapacity = $roomSelection->quantity * $roomSelection->capacity;
+        // In edit mode, use maxQuantity which includes available rooms beyond the booked count.
+        // In create mode, use quantity which is the user's room selection from step 1.
+        if (BookingDto::MODE_EDIT === $bookingDto->getMode()) {
+            $effectiveQuantity = $roomSelection->maxQuantity;
+        } else {
+            $effectiveQuantity = $roomSelection->quantity ?? 0;
+        }
+        $totalCapacity = $effectiveQuantity * $roomSelection->capacity;
 
         // Count current occupancy (excluding current participant)
         $occupancy = 0;
@@ -174,7 +181,12 @@ class ParticipantAssignedRoomFieldHandler extends AbstractParticipantFieldHandle
             return; // Shouldn't happen
         }
 
-        $totalCapacity = $roomSelection->quantity * $roomSelection->capacity;
+        if (BookingDto::MODE_EDIT === $bookingDto->getMode()) {
+            $effectiveQuantity = $roomSelection->maxQuantity;
+        } else {
+            $effectiveQuantity = $roomSelection->quantity ?? 0;
+        }
+        $totalCapacity = $effectiveQuantity * $roomSelection->capacity;
         $currentOccupancy = count($participantsWithRoom);
         $spacesNeeded = ($currentOccupancy + 1) - $totalCapacity;
 
diff --git a/src/Service/ParticipantCardDataService.php b/src/Service/ParticipantCardDataService.php
index fc7edf6..904355c 100644
--- a/src/Service/ParticipantCardDataService.php
+++ b/src/Service/ParticipantCardDataService.php
@@ -237,8 +237,8 @@ class ParticipantCardDataService
         } else {
             $groups[] = 'booking_edit';
 
-            // In edit mode, add strict_required only if applicant is immutable
-            if (false === ($bookingDto->participants[0]?->mutable ?? true)) {
+            // Strict validation in edit mode except for internal agency bookings
+            if (false === $bookingDto->isInternalAgencyBooking()) {
                 $groups[] = 'strict_required';
             }
         }
diff --git a/src/Service/RoomPricingCalculator.php b/src/Service/RoomPricingCalculator.php
index 81cc799..4f2ea2c 100644
--- a/src/Service/RoomPricingCalculator.php
+++ b/src/Service/RoomPricingCalculator.php
@@ -135,6 +135,10 @@ class RoomPricingCalculator
             }
         }
 
+        // Count current participant assignments from the DTO (reflects live state
+        // including new assignments not yet in the booking entity)
+        $assignmentCounts = $bookingDto->getRoomAssignmentCounts();
+
         // Build pricing array
         foreach ($roomGroups as $roomId => $data) {
             $room = $data['room'];
@@ -144,10 +148,14 @@ class RoomPricingCalculator
             // Calculate average unit price (price per person)
             $unitPrice = $participantCount > 0 ? $totalPrice / $participantCount : 0.0;
 
+            // Use live assignment count for quantity display so the sidebar reflects
+            // new room assignments that haven't been persisted to the booking entity yet
+            $quantity = $assignmentCounts[$roomId] ?? $room->totalCount;
+
             $roomPricing[] = [
                 'roomId' => $room->id,
                 'label' => $room->label,
-                'quantity' => $room->totalCount,
+                'quantity' => $quantity,
                 'participantCount' => $participantCount,
                 'unitPrice' => $unitPrice,
                 'totalPrice' => $totalPrice,
diff --git a/templates/booking/_summary.html.twig b/templates/booking/_summary.html.twig
index 3347b0c..54ecadd 100644
--- a/templates/booking/_summary.html.twig
+++ b/templates/booking/_summary.html.twig
@@ -104,6 +104,18 @@
                             {% endif %}
                         </td>
                     </tr>
+                    <tr>
+                        <td class="p-2 align-top">
+                            Unterkunft
+                        </td>
+                        <td class="p-2 align-top w-24 text-right whitespace-nowrap">
+                            {% if mutableData.items['accommodation'].mutable %}
+                                {{ mutableData.items['accommodation'].mutableBefore|date('d.m.Y') }}
+                            {% else %}
+                                nicht mehr möglich
+                            {% endif %}
+                        </td>
+                    </tr>
                 </table>
             </div>
         {% endif %}
diff --git a/tests/Form/Model/ParticipantEditDtoTest.php b/tests/Form/Model/ParticipantEditDtoTest.php
index 69458de..f71f0da 100644
--- a/tests/Form/Model/ParticipantEditDtoTest.php
+++ b/tests/Form/Model/ParticipantEditDtoTest.php
@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace App\Tests\Form\Model;
 
 use App\BusProNet\Model\Travel;
+use App\BusProNet\XmlLoader\AgencyLoader;
 use App\Form\Model\BookingDto;
 use App\Form\Model\ParticipantDto;
 use App\Form\Model\ParticipantEditDto;
@@ -373,6 +374,46 @@ class ParticipantEditDtoTest extends TestCase
         $this->assertCount(0, $violations5);
     }
 
+    public function testInternalAgencyBookingSkipsEmailUniqueness(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createAdultParticipant('shared@ep-reisen.de'),
+            $this->createAdultParticipant('shared@ep-reisen.de'),
+            $this->createAdultParticipant('shared@ep-reisen.de'),
+        ]);
+
+        // Mark as internal agency booking
+        $bookingDto->agencyCode = AgencyLoader::INTERNAL_AGENCY_CODE;
+
+        // Validate second participant (non-applicant adult with duplicate email)
+        $wrapper = new ParticipantEditDto(
+            participant: $bookingDto->participants[1],
+            bookingContext: $bookingDto,
+        );
+
+        $violations = $this->validator->validate($wrapper, null, ['booking_create']);
+
+        $this->assertCount(0, $violations, 'Internal agency bookings should skip email uniqueness validation');
+    }
+
+    public function testNonAgencyBookingStillEnforcesEmailUniqueness(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createAdultParticipant('shared@example.com'),
+            $this->createAdultParticipant('shared@example.com'),
+        ]);
+
+        // Non-agency booking (default agencyCode is null)
+        $wrapper = new ParticipantEditDto(
+            participant: $bookingDto->participants[1],
+            bookingContext: $bookingDto,
+        );
+
+        $violations = $this->validator->validate($wrapper, null, ['booking_create']);
+
+        $this->assertCount(1, $violations, 'Non-agency bookings should still enforce email uniqueness');
+    }
+
     // =========================================
     // Ski Pass Validation Tests (Baby Age Exemption)
     // =========================================
diff --git a/tests/Form/Service/Condition/AccommodationMutabilityConditionTest.php b/tests/Form/Service/Condition/AccommodationMutabilityConditionTest.php
new file mode 100644
index 0000000..864a8a9
--- /dev/null
+++ b/tests/Form/Service/Condition/AccommodationMutabilityConditionTest.php
@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Form\Service\Condition;
+
+use App\BusProNet\Model\Travel;
+use App\Form\Model\BookingDto;
+use App\Form\Service\Condition\AccommodationMutabilityCondition;
+use PHPUnit\Framework\TestCase;
+
+class AccommodationMutabilityConditionTest extends TestCase
+{
+    private AccommodationMutabilityCondition $condition;
+
+    protected function setUp(): void
+    {
+        $this->condition = new AccommodationMutabilityCondition();
+    }
+
+    public function testReturnsFalseWhenRoomsMutable(): void
+    {
+        $travel = new Travel();
+        $travel->roomsMutable = true;
+
+        $bookingDto = new BookingDto($travel, 1);
+
+        $result = $this->condition->evaluate($bookingDto, 0, []);
+
+        $this->assertFalse($result, 'Should return false when rooms are mutable (field should be editable)');
+    }
+
+    public function testReturnsTrueWhenRoomsNotMutable(): void
+    {
+        $travel = new Travel();
+        $travel->roomsMutable = false;
+
+        $bookingDto = new BookingDto($travel, 1);
+
+        $result = $this->condition->evaluate($bookingDto, 0, []);
+
+        $this->assertTrue($result, 'Should return true when rooms are not mutable (field should be static text)');
+    }
+
+    public function testDefaultTravelHasMutableRooms(): void
+    {
+        $travel = new Travel();
+
+        $bookingDto = new BookingDto($travel, 1);
+
+        $result = $this->condition->evaluate($bookingDto, 0, []);
+
+        $this->assertFalse($result, 'Default travel should have mutable rooms');
+    }
+
+    public function testGetDependentFieldsReturnsEmptyArray(): void
+    {
+        $result = $this->condition->getDependentFields();
+
+        $this->assertIsArray($result);
+        $this->assertEmpty($result);
+    }
+
+    public function testGetDescriptionReturnsString(): void
+    {
+        $result = $this->condition->getDescription();
+
+        $this->assertIsString($result);
+        $this->assertStringContainsString('not mutable', $result);
+    }
+}