First of all, this is not intended to be taken as expert advice by any means. It's just a personal experience that may help spark a possibility.
A while back, I had chained my old Roland module through my DM10 using MIDI cables. I have an old Yamaha keyboard that has no working external speaker, so I use my Roland module to provide sounds for the keyboard. For some strange reason, I connected the keyboard to the Roland, the Roland to the DM10, and then the DM10 to my PC. After messing around with settings a bit, I was able to trigger from either module using the keyboard and pads connected to both. Could something like this at least be a start to what you are trying to accomplish?
I know there are a lot of holes in my method, as I can't even remember what software I was using at the time, but it seemed to work similarly to what you are trying to do. My exercise was just a trial-and-error one, but I though it may help a bit!
I apologize in advance if it ends up leading nowhere!
--Shawn