diff --git a/src/test/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerControllerAcceptanceTest.java b/src/test/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerControllerAcceptanceTest.java
index a3d5e4c4..3f396d31 100644
--- a/src/test/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerControllerAcceptanceTest.java
+++ b/src/test/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerControllerAcceptanceTest.java
@@ -21,6 +21,7 @@ import org.springframework.transaction.annotation.Transactional;
 
 import java.util.UUID;
 
+import static net.hostsharing.hsadminng.hs.office.relation.HsOfficeRelationType.EX_PARTNER;
 import static net.hostsharing.test.IsValidUuidMatcher.isUuidValid;
 import static net.hostsharing.test.JsonMatcher.lenientlyEquals;
 import static org.assertj.core.api.Assertions.assertThat;
@@ -41,7 +42,7 @@ class HsOfficePartnerControllerAcceptanceTest extends ContextBasedTestWithCleanu
     HsOfficePartnerRepository partnerRepo;
 
     @Autowired
-    HsOfficeRelationRepository relationRepository;
+    HsOfficeRelationRepository relationRepo;
 
     @Autowired
     HsOfficePersonRepository personRepo;
@@ -376,6 +377,45 @@ class HsOfficePartnerControllerAcceptanceTest extends ContextBasedTestWithCleanu
                     });
         }
 
+        @Test
+        void patchingThePartnerRelCreatesExPartnerRel() {
+
+            context.define("superuser-alex@hostsharing.net");
+            final var givenPartner = givenSomeTemporaryPartnerBessler(20011);
+            final var givenPartnerRel = givenSomeTemporaryPartnerRel("Third OHG", "third contact");
+
+            RestAssured // @formatter:off
+                    .given()
+                        .header("current-user", "superuser-alex@hostsharing.net")
+                        .contentType(ContentType.JSON)
+                        .body("""
+                                {
+                                   "partnerRelUuid": "%s"
+                                }
+                                """.formatted(givenPartnerRel.getUuid()))
+                        .port(port)
+                    .when()
+                        .patch("http://localhost/api/hs/office/partners/" + givenPartner.getUuid())
+                    .then().log().body()
+                        .assertThat().statusCode(200);
+            // @formatter:on
+
+            // then the partner got actually updated
+            context.define("superuser-alex@hostsharing.net");
+            assertThat(partnerRepo.findByUuid(givenPartner.getUuid())).isPresent().get()
+                    .matches(partner -> {
+                        assertThat(partner.getPartnerRel().getHolder().getTradeName()).isEqualTo("Third OHG");
+                        assertThat(partner.getPartnerRel().getContact().getLabel()).isEqualTo("third contact");
+                        return true;
+                    });
+
+            // and an ex-partner-relation got created
+            final var partnerPersonUUid = givenPartner.getPartnerRel().getAnchor().getUuid();
+            assertThat(relationRepo.findRelationRelatedToPersonUuidAndRelationType(partnerPersonUUid, EX_PARTNER))
+                    .map(HsOfficeRelationEntity::toShortString)
+                    .contains("xxx");
+        }
+
         @Test
         void globalAdmin_withoutAssumedRole_canPatchPartialPropertiesOfArbitraryPartner() {
 
@@ -442,7 +482,7 @@ class HsOfficePartnerControllerAcceptanceTest extends ContextBasedTestWithCleanu
 
             // then the given partner is gone
             assertThat(partnerRepo.findByUuid(givenPartner.getUuid())).isEmpty();
-            assertThat(relationRepository.findByUuid(givenPartner.getPartnerRel().getUuid())).isEmpty();
+            assertThat(relationRepo.findByUuid(givenPartner.getPartnerRel().getUuid())).isEmpty();
         }
 
         @Test