‘Pass through’ question

I have a process that uses a pre-proc to determine how inbound messages are to be processed.  Some are going to a regular xlate and others are

simply a ‘pass through’ from point A to point B.  

The pass through messages have the message ID at the start of each record.  Is there a way to set up the threads so that ID isn’t included on the outbound message?  Or will I need a post-proc to do that?

Thanks.