Sage 100

Has anyone developed a script to merge salesperson's?

Where? There is a utility in AR Utilities (Global Customer Field change) that does that.

The Global Customer Field change can change the salesperson in customer records, but not salesperson's commission history.

I found that if you delete the unwanted salesperson records in DFDM and run salesperson history, commission, etc. reports they do not error out. Instead, they show with **Not on file** next to the salesperson code or in some cases just show a blank salesperson name. That will suffice in this customer's case as they have all the history reports in PDF. So all they need is a nice, clean file going forward.