diff --git a/src/Bundle/ChillPersonBundle/Service/AccompanyingPeriodWork/AccompanyingPeriodWorkMergeService.php b/src/Bundle/ChillPersonBundle/Service/AccompanyingPeriodWork/AccompanyingPeriodWorkMergeService.php
index 155a180a7..4b48ffcbf 100644
--- a/src/Bundle/ChillPersonBundle/Service/AccompanyingPeriodWork/AccompanyingPeriodWorkMergeService.php
+++ b/src/Bundle/ChillPersonBundle/Service/AccompanyingPeriodWork/AccompanyingPeriodWorkMergeService.php
@@ -12,7 +12,7 @@ declare(strict_types=1);
 namespace Chill\PersonBundle\Service\AccompanyingPeriodWork;
 
 use Chill\PersonBundle\Entity\AccompanyingPeriod\AccompanyingPeriodWork;
-use Doctrine\Common\Collections\Collection;
+use Doctrine\DBAL\Exception;
 use Doctrine\ORM\EntityManagerInterface;
 use Doctrine\ORM\Mapping\ClassMetadata;
 
@@ -20,6 +20,9 @@ class AccompanyingPeriodWorkMergeService
 {
     public function __construct(private readonly EntityManagerInterface $em) {}
 
+    /**
+     * @throws Exception
+     */
     public function merge(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
     {
         // Transfer non-duplicate data
@@ -32,96 +35,140 @@ class AccompanyingPeriodWorkMergeService
         $this->em->flush();
     }
 
+    /**
+     * @throws Exception
+     */
     private function transferData(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
     {
-        $excludedProperties = ['id', 'createdAt', 'createdBy', 'updatedAt', 'updatedBy'];
-        $reflection = new \ReflectionClass(AccompanyingPeriodWork::class);
+        $conn = $this->em->getConnection();
 
-        foreach ($reflection->getProperties() as $property) {
-            if (in_array($property->getName(), $excludedProperties, true)) {
-                continue;
-            }
-
-            $toKeepValue = $property->getValue($toKeep);
-            $toDeleteValue = $property->getValue($toDelete);
-
-            if (null === $toKeepValue && null !== $toDeleteValue) {
-                $property->setValue($toKeep, $toDeleteValue);
-            }
-
-            if ($toKeepValue instanceof Collection
-                && $toDeleteValue instanceof Collection) {
-                foreach ($toDeleteValue as $item) {
-                    if (!$toKeepValue->contains($item)) {
-                        $toKeepValue->add($item);
-                    }
-                }
+        $sqlStatements = [
+            $this->generateStartDateSQL(),
+            $this->generateEndDateSQL(),
+            $this->generateCommentSQL(),
+        ];
+
+        $conn->beginTransaction();
+
+        try {
+            foreach ($sqlStatements as $sql) {
+                $conn->executeQuery($sql, ['toDelete' => $toDelete->getId(), 'toKeep' => $toKeep->getId()]);
             }
+            $conn->commit();
+        } catch (\Exception $e) {
+            $conn->rollBack();
+            throw $e;
         }
     }
 
+    private function generateStartDateSQL(): string
+    {
+        return '
+            UPDATE chill_person_accompanying_period_work
+            SET startdate = LEAST(
+                COALESCE((SELECT startdate FROM chill_person_accompanying_period_work WHERE id = :toDelete), startdate),
+                startdate
+            )
+            WHERE id = :toKeep';
+    }
+
+    private function generateEndDateSQL(): string
+    {
+        return '
+            UPDATE chill_person_accompanying_period_work
+            SET enddate =
+                CASE
+                    WHEN (SELECT enddate FROM chill_person_accompanying_period_work WHERE id = :toDelete) IS NULL
+                        OR enddate IS NULL
+                    THEN NULL
+                    ELSE GREATEST(
+                        COALESCE((SELECT enddate FROM chill_person_accompanying_period_work WHERE id = :toDelete), enddate),
+                        enddate
+                    )
+                END
+            WHERE id = :toKeep';
+    }
+
+    private function generateCommentSQL(): string
+    {
+        return "
+            UPDATE chill_person_accompanying_period_work
+            SET note = CONCAT_WS(
+                '\n',
+                NULLIF(TRIM(note), ''),
+                NULLIF(TRIM((SELECT note FROM chill_person_accompanying_period_work WHERE id = :toDelete)), '')
+            )
+            WHERE id = :toKeep";
+    }
+
+    /**
+     * @throws Exception
+     */
     private function updateReferences(AccompanyingPeriodWork $toKeep, AccompanyingPeriodWork $toDelete): void
     {
         $allMeta = $this->em->getMetadataFactory()->getAllMetadata();
+        $conn = $this->em->getConnection();
+        $sqlStatements = [];
 
         foreach ($allMeta as $meta) {
+            if ($meta->isMappedSuperclass) {
+                continue;
+            }
+
             foreach ($meta->getAssociationMappings() as $assoc) {
                 if (AccompanyingPeriodWork::class !== $assoc['targetEntity']) {
-                    continue; // Skip unrelated associations
+                    continue;
                 }
 
-                $entityClass = $meta->getName();
-                $associationField = $assoc['fieldName'];
-
                 if ($assoc['type'] & ClassMetadata::TO_ONE) {
-                    // Handle ManyToOne or OneToOne
-                    $qb = $this->em->createQueryBuilder();
-                    $qb->update($entityClass, 'e')
-                        ->set("e.{$associationField}", ':toKeep')
-                        ->where("e.{$associationField} = :toDelete")
-                        ->setParameter('toKeep', $toKeep)
-                        ->setParameter('toDelete', $toDelete)
-                        ->getQuery()
-                        ->execute();
+                    if ('handlingThirdparty' === $assoc['fieldName']) {
+                        continue;
+                    }
+                    $sqlStatements[] = $this->generateToOneUpdateQuery($meta, $assoc);
                 }
 
                 if ($assoc['type'] & ClassMetadata::TO_MANY) {
-                    // Handle ManyToMany or OneToMany (inverse side)
-                    $repo = $this->em->getRepository($entityClass);
-                    $linkedEntities = $repo->createQueryBuilder('e')
-                        ->join("e.{$associationField}", 't')
-                        ->where('t = :toDelete')
-                        ->setParameter('toDelete', $toDelete)
-                        ->getQuery()
-                        ->getResult();
-
-                    foreach ($linkedEntities as $entity) {
-                        $getter = 'get'.ucfirst($associationField);
-                        $setter = 'set'.ucfirst($associationField);
-                        $adder = 'add'.ucfirst(rtrim($associationField, 's'));
-                        $remover = 'remove'.ucfirst(rtrim($associationField, 's'));
-
-                        if (method_exists($entity, $getter) && method_exists($entity, $setter)) {
-                            // For OneToMany owning side
-                            $collection = $entity->{$getter}();
-                            if ($collection->contains($toDelete)) {
-                                $collection->removeElement($toDelete);
-                                if (!$collection->contains($toKeep)) {
-                                    $collection->add($toKeep);
-                                }
-                            }
-                        } elseif (method_exists($entity, $adder) && method_exists($entity, $remover)) {
-                            // For ManyToMany
-                            $entity->{$remover}($toDelete);
-                            $entity->{$adder}($toKeep);
-                        }
-
-                        $this->em->persist($entity);
+                    if (!isset($assoc['joinTable'])) {
+                        continue;
                     }
+                    $sqlStatements = array_merge($sqlStatements, $this->generateToManyUpdateQueries($assoc));
                 }
             }
         }
 
-        $this->em->flush();
+        $conn->beginTransaction();
+        try {
+            foreach ($sqlStatements as $sql) {
+                $conn->executeStatement($sql, ['toDelete' => $toDelete->getId(), 'toKeep' => $toKeep->getId()]);
+            }
+            $conn->commit();
+        } catch (\Exception $e) {
+            $conn->rollBack();
+            throw $e;
+        }
+    }
+
+    private function generateToOneUpdateQuery(ClassMetadata $meta, array $assoc): string
+    {
+        $tableName = $meta->getTableName();
+        $joinColumn = $meta->getSingleAssociationJoinColumnName($assoc['fieldName']);
+
+        return "UPDATE {$tableName} SET {$joinColumn} = :toKeep WHERE {$joinColumn} = :toDelete";
+    }
+
+    private function generateToManyUpdateQueries(array $assoc): array
+    {
+        $sqls = [];
+        $joinTable = $assoc['joinTable']['name'];
+        $owningColumn = $assoc['joinTable']['joinColumns'][0]['name'];
+        $inverseColumn = $assoc['joinTable']['inverseJoinColumns'][0]['name'];
+
+        // Insert relations, skip already existing ones
+        $sqls[] = "INSERT IGNORE INTO {$joinTable} ({$owningColumn}, {$inverseColumn})
+                SELECT :toKeep, {$inverseColumn} FROM {$joinTable} WHERE {$owningColumn} = :toDelete";
+        // Delete old references
+        $sqls[] = "DELETE FROM {$joinTable} WHERE {$owningColumn} = :toDelete";
+
+        return $sqls;
     }
 }