Bernie - One option is to switch from USB to using basic MIDI connections. As you know the SD40 has two MIDI ins. Under the covers that gives you access to 32 independent MIDI channels. You could run one of the controllers to In1 (this is limited to using the GM voices) and the other to In2 (This will allow access to the arranger and the voice presets). In the MIDI map, you would use the "GM Part" button to configure whatever channel is needed for In1 and the "Arranger" button to configure whatever MIDI channel is needed for the In2 port. Of course, that assumes you can run MIDI vs. USB connections?