Sounds like you need better filters in vArranger, to stop MIDI commands coming FROM the Audya getting looped back into the Audya...

And possibly some better MIDI implementation in the Audya to determine if a switch or slider sends on MIDI only, or whether it should control the Audya only, or both...

I don't often get much support here when I go off on one of my rants about how BAD most arranger's MIDI implementation is, and how much more the manufacturers could do to standardize the MIDI codes for most basic arranger operation, but here is a perfect example of why we NEED this kind of stuff. The minute you want to use your arranger with something else, anything else, you start bumping into this kind of thing.

Keep the pressure up on the manufacturers to NOT turn arrangers into standalone products that are very difficult to integrate into an entire MIDI system...