diff --git a/src/main/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemController.java b/src/main/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemController.java
index 88f3a4e9..f28d418d 100644
--- a/src/main/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemController.java
+++ b/src/main/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemController.java
@@ -17,8 +17,6 @@ import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;
 
-import jakarta.persistence.EntityManager;
-import jakarta.persistence.PersistenceContext;
 import java.time.LocalDate;
 import java.util.List;
 import java.util.UUID;
diff --git a/src/main/java/net/hostsharing/hsadminng/hs/office/sepamandate/HsOfficeSepaMandateController.java b/src/main/java/net/hostsharing/hsadminng/hs/office/sepamandate/HsOfficeSepaMandateController.java
index 9511bdd6..1ccfb457 100644
--- a/src/main/java/net/hostsharing/hsadminng/hs/office/sepamandate/HsOfficeSepaMandateController.java
+++ b/src/main/java/net/hostsharing/hsadminng/hs/office/sepamandate/HsOfficeSepaMandateController.java
@@ -1,6 +1,8 @@
 package net.hostsharing.hsadminng.hs.office.sepamandate;
 
 import net.hostsharing.hsadminng.context.Context;
+import net.hostsharing.hsadminng.hs.office.bankaccount.HsOfficeBankAccountEntity;
+import net.hostsharing.hsadminng.hs.office.debitor.HsOfficeDebitorEntity;
 import net.hostsharing.hsadminng.hs.office.generated.api.v1.api.HsOfficeSepaMandatesApi;
 import net.hostsharing.hsadminng.hs.office.generated.api.v1.model.HsOfficeSepaMandateInsertResource;
 import net.hostsharing.hsadminng.hs.office.generated.api.v1.model.HsOfficeSepaMandatePatchResource;
@@ -135,6 +137,8 @@ public class HsOfficeSepaMandateController implements HsOfficeSepaMandatesApi {
     };
 
     final BiConsumer<HsOfficeSepaMandateInsertResource, HsOfficeSepaMandateEntity> SEPA_MANDATE_RESOURCE_TO_ENTITY_POSTMAPPER = (resource, entity) -> {
+        entity.setDebitor(mapper.fetchEntity(HsOfficeDebitorEntity.class, resource.getDebitorUuid()));
+        entity.setBankAccount(mapper.fetchEntity(HsOfficeBankAccountEntity.class, resource.getBankAccountUuid()));
         entity.setValidity(toPostgresDateRange(resource.getValidFrom(), resource.getValidTo()));
     };
 }
diff --git a/src/main/java/net/hostsharing/hsadminng/mapper/Mapper.java b/src/main/java/net/hostsharing/hsadminng/mapper/Mapper.java
index b16db84b..91dc725d 100644
--- a/src/main/java/net/hostsharing/hsadminng/mapper/Mapper.java
+++ b/src/main/java/net/hostsharing/hsadminng/mapper/Mapper.java
@@ -26,6 +26,7 @@ public class Mapper extends ModelMapper {
     EntityManager em;
 
     public Mapper() {
+        // make sure that resource.whateverUuid does not get mapped to entity.uuid, if resource.uuid does not exist
         getConfiguration().setMatchingStrategy(STRICT);
     }
 
@@ -67,7 +68,7 @@ public class Mapper extends ModelMapper {
             if (subEntityUuid == null) {
                 continue;
             }
-            ReflectionUtils.setField(f, target, findEntityById(f.getType(), subEntityUuid));
+            ReflectionUtils.setField(f, target, fetchEntity(f.getType(), subEntityUuid));
         }
         return target;
     }
@@ -83,9 +84,9 @@ public class Mapper extends ModelMapper {
             .toArray(Field[]::new);
     }
 
-    private Object findEntityById(final Class<?> entityClass, final Object subEntityUuid) {
+    public <E> E fetchEntity(final Class<E> entityClass, final Object subEntityUuid) {
         // using getReference would be more efficent, but results in very technical error messages
-        final var entity = em.find(entityClass, subEntityUuid);
+        final var entity = em.find(entityClass, subEntityUuid); // FIXME: try getReference
         if (entity != null) {
             return entity;
         }