I have a similar question and hope you might be able to answer:

I'm sending a midi tempo from an external device, to two Factors. The PF is first, the TF is second. To make them sync, the PF has to be set to Output XMT. If it's set to THRU, the TF cannot lock in on the tempo. But when I also send the PF and TF each a Program Change from my Midi Mitigator (RFC-1), the message does not transmit via the PF to the TF unless the PF is set to THRU (which then defeats the clock). 

I have set up a map, but it seems only to work when using the PF buttons themselves and not when receiving a message from the RFC-1. (I'll mess around with this some more to make sure, but my primary objective is to have the RFC-1 transmit its multiple messages to each unit AND to allow the tempo info to be intact. I do have the channel numbers correct.

Thanks in advance… Paul