diff --git a/src/main/kotlin/com/android/trisolarisserver/controller/Guests.kt b/src/main/kotlin/com/android/trisolarisserver/controller/Guests.kt
index e05778f..c736e04 100644
--- a/src/main/kotlin/com/android/trisolarisserver/controller/Guests.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/controller/Guests.kt
@@ -8,6 +8,7 @@ import com.android.trisolarisserver.controller.dto.GuestVehicleRequest
 import com.android.trisolarisserver.models.booking.Guest
 import com.android.trisolarisserver.models.booking.GuestVehicle
 import com.android.trisolarisserver.db.repo.BookingRepo
+import com.android.trisolarisserver.db.repo.GuestDocumentRepo
 import com.android.trisolarisserver.db.repo.GuestRepo
 import com.android.trisolarisserver.db.repo.GuestRatingRepo
 import com.android.trisolarisserver.repo.AppUserRepo
@@ -19,6 +20,7 @@ import org.springframework.http.HttpStatus
 import org.springframework.http.MediaType
 import org.springframework.http.ResponseEntity
 import org.springframework.security.core.annotation.AuthenticationPrincipal
+import org.springframework.transaction.annotation.Transactional
 import org.springframework.web.bind.annotation.*
 import org.springframework.web.multipart.MultipartFile
 import org.springframework.web.server.ResponseStatusException
@@ -34,12 +36,14 @@ class Guests(
     private val bookingRepo: BookingRepo,
     private val guestVehicleRepo: GuestVehicleRepo,
     private val guestRatingRepo: GuestRatingRepo,
+    private val guestDocumentRepo: GuestDocumentRepo,
     private val signatureStorage: GuestSignatureStorage,
     private val appUserRepo: AppUserRepo
 ) {
 
     @PostMapping
     @ResponseStatus(HttpStatus.CREATED)
+    @Transactional
     fun createGuest(
         @PathVariable propertyId: UUID,
         @AuthenticationPrincipal principal: MyPrincipal?,
@@ -55,15 +59,26 @@ class Guests(
         if (booking.property.id != property.id) {
             throw ResponseStatusException(HttpStatus.BAD_REQUEST, "Booking not in property")
         }
-        if (booking.primaryGuest != null) {
-            throw ResponseStatusException(HttpStatus.CONFLICT, "Booking already linked to guest")
+        val currentGuest = booking.primaryGuest
+        if (currentGuest != null && phone == null) {
+            if (!isPlaceholderGuest(currentGuest)) {
+                throw ResponseStatusException(HttpStatus.CONFLICT, "Booking already linked to guest")
+            }
+            val updated = applyGuestDetails(currentGuest, request)
+            booking.updatedAt = OffsetDateTime.now()
+            bookingRepo.save(booking)
+            return setOf(updated).toResponse(propertyId, guestVehicleRepo, guestRatingRepo).first()
         }
         if (phone != null) {
             val existing = guestRepo.findByPropertyIdAndPhoneE164(propertyId, phone)
             if (existing != null) {
+                val previous = booking.primaryGuest
                 booking.primaryGuest = existing
                 booking.updatedAt = OffsetDateTime.now()
                 bookingRepo.save(booking)
+                if (previous != null && previous.id != existing.id && isPlaceholderGuest(previous) && isSafeToDelete(previous)) {
+                    guestRepo.delete(previous)
+                }
                 return setOf(existing).toResponse(propertyId, guestVehicleRepo, guestRatingRepo).first()
             }
         }
@@ -196,6 +211,33 @@ class Guests(
             .body(resource)
     }
 
+    private fun applyGuestDetails(guest: Guest, request: GuestCreateRequest): Guest {
+        val name = request.name?.trim()?.ifBlank { null }
+        val nationality = request.nationality?.trim()?.ifBlank { null }
+        val address = request.addressText?.trim()?.ifBlank { null }
+        if (name != null) guest.name = name
+        if (nationality != null) guest.nationality = nationality
+        if (address != null) guest.addressText = address
+        guest.updatedAt = OffsetDateTime.now()
+        return guestRepo.save(guest)
+    }
+
+    private fun isPlaceholderGuest(guest: Guest): Boolean {
+        return guest.phoneE164.isNullOrBlank() &&
+            guest.name.isNullOrBlank() &&
+            guest.nationality.isNullOrBlank() &&
+            guest.addressText.isNullOrBlank() &&
+            guest.signaturePath.isNullOrBlank()
+    }
+
+    private fun isSafeToDelete(guest: Guest): Boolean {
+        val id = guest.id ?: return false
+        if (bookingRepo.countByPrimaryGuestId(id) > 0) return false
+        if (guestVehicleRepo.existsByGuestId(id)) return false
+        if (guestDocumentRepo.existsByGuestId(id)) return false
+        if (guestRatingRepo.existsByGuestId(id)) return false
+        return true
+    }
 }
 
 private fun Set<Guest>.toResponse(
diff --git a/src/main/kotlin/com/android/trisolarisserver/db/repo/BookingRepo.kt b/src/main/kotlin/com/android/trisolarisserver/db/repo/BookingRepo.kt
index 6b441fc..78a1697 100644
--- a/src/main/kotlin/com/android/trisolarisserver/db/repo/BookingRepo.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/db/repo/BookingRepo.kt
@@ -7,4 +7,5 @@ import java.util.UUID
 interface BookingRepo : JpaRepository<Booking, UUID> {
     fun findByPropertyIdAndSourceBookingId(propertyId: UUID, sourceBookingId: String): Booking?
     fun existsByPropertyIdAndSourceBookingId(propertyId: UUID, sourceBookingId: String): Boolean
+    fun countByPrimaryGuestId(guestId: UUID): Long
 }
diff --git a/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestDocumentRepo.kt b/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestDocumentRepo.kt
index 034066f..bdc4b62 100644
--- a/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestDocumentRepo.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestDocumentRepo.kt
@@ -7,4 +7,5 @@ import java.util.UUID
 interface GuestDocumentRepo : JpaRepository<GuestDocument, UUID> {
     fun findByPropertyIdAndGuestIdOrderByUploadedAtDesc(propertyId: UUID, guestId: UUID): List<GuestDocument>
     fun findByIdAndPropertyIdAndGuestId(id: UUID, propertyId: UUID, guestId: UUID): GuestDocument?
+    fun existsByGuestId(guestId: UUID): Boolean
 }
diff --git a/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestRatingRepo.kt b/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestRatingRepo.kt
index f87b1e2..a8d09f6 100644
--- a/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestRatingRepo.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/db/repo/GuestRatingRepo.kt
@@ -9,6 +9,7 @@ import java.util.UUID
 interface GuestRatingRepo : JpaRepository<GuestRating, UUID> {
     fun findByGuestIdOrderByCreatedAtDesc(guestId: UUID): List<GuestRating>
     fun existsByGuestIdAndBookingId(guestId: UUID, bookingId: UUID): Boolean
+    fun existsByGuestId(guestId: UUID): Boolean
 
     @Query(
         """
diff --git a/src/main/kotlin/com/android/trisolarisserver/repo/GuestVehicleRepo.kt b/src/main/kotlin/com/android/trisolarisserver/repo/GuestVehicleRepo.kt
index d3a3b1f..75f9943 100644
--- a/src/main/kotlin/com/android/trisolarisserver/repo/GuestVehicleRepo.kt
+++ b/src/main/kotlin/com/android/trisolarisserver/repo/GuestVehicleRepo.kt
@@ -8,4 +8,5 @@ interface GuestVehicleRepo : JpaRepository<GuestVehicle, UUID> {
     fun findByPropertyIdAndVehicleNumberIgnoreCase(propertyId: UUID, vehicleNumber: String): GuestVehicle?
     fun findByGuestIdIn(guestIds: List<UUID>): List<GuestVehicle>
     fun existsByPropertyIdAndVehicleNumberIgnoreCase(propertyId: UUID, vehicleNumber: String): Boolean
+    fun existsByGuestId(guestId: UUID): Boolean
 }