Index: t3lib/class.t3lib_tcemain.php
===================================================================
--- t3lib/class.t3lib_tcemain.php	(.../tags/t3_410)	(Revision 22)
+++ t3lib/class.t3lib_tcemain.php	(.../branches/bug-3531)	(Revision 79)
@@ -3957,6 +3957,20 @@
 											}
 										}
 
+										// traverse through all columns and check for mm-refs to update
+										foreach ($TCA[$table]['columns'] as $col) {
+											if ($col['config']['MM'] != '') {
+												// first swap the records for the new element to the negative uid
+												$GLOBALS['TYPO3_DB']->exec_UPDATEquery($col['config']['MM'], 'uid_foreign='.$swapWith, Array('uid_foreign' => -$swapWith));
+												
+												// then swap the old record to the new uid
+												$GLOBALS['TYPO3_DB']->exec_UPDATEquery($col['config']['MM'], 'uid_foreign='.$id, Array('uid_foreign' => $swapWith));
+												
+												// and then finally swap the new record to the old uid
+												$GLOBALS['TYPO3_DB']->exec_UPDATEquery($col['config']['MM'], 'uid_foreign=-'.$swapWith, Array('uid_foreign' => $id));
+											}
+										}
+										
 										if (!count($sqlErrors))	{
 
 												// Checking for delete: