Yes, that is one issue with multiple updates, you need a way to uniquely identify the records you want to update.
with a multiple update procedure, that can become difficult if you use a unique identifier that is also included in records you dont wish to update.
the multiplle update procedure uses the WADA_RepeatID_DetailOrderID hidden form element and the ID column you specify to create the WHERE clause of the update statement to determine which records to update.
You could set the WADA_RepeatID_DetailOrderID hidden form element to Use the DetailID column from the recordset as the value and set the ID column in the multiple update procedure to use the DetailID column as the ID column.