How do I prevent ST orders from updating P4115 sales history? P400391 does not seem to work for thi

We are using the ST/OT process to move items from our warehouse branch to a mobile retail trailer that we are starting up.  We would like to exclude the ST from P4115 item history.  My understanding is that this can be done by adding a record for the branch to the ST doc type in P400391 which is accessed by a row exit from P40040.  I have tried this in several ways but it continues to record the transaction in P4115.  It there some other process that needs to be run or setting to change to make this effective?