Ok, I just double checked a received program change message is sent through the transmit map as well. So, you can set-up both maps so that:
Received program change 1 loads preset 10 which transmits program change 20 when it's loaded
But what's important to understand is that you're not mapping program change 1 to program change 20. You're mapping program change 1 to load a particular preset number, and that particular preset number can be mapped to send out a different program change number when it's loaded.
