I'm running DW2017, so not sure if I can get the WA UI up these days.
But I basically need to store the first InsertID into a session, and then instead of:
<input type="hidden" name="UserIDIT" id="UserIDIT" value="<?php echo ["[InsertID]"]; ?>" />
Have
<input type="hidden" name="UserIDIT" id="UserIDIT" value="<?php echo($_SESSION['SaveAsName']); ?>" />
?