Boris That is a very complicated way to get multitrack outputs, is there a reason to why you want to do this, can you explain?
You might end up with syncing problem, and a very messy work environment, why dont you just use one device and multitrack on it as it was intended, and an output device that keeps the multitracks seperate in to your mixer for separate mixer control, this is a lot more solid and simpler way of achieving seperate outputs.
Yes you can possibly do it your way but it sounds like a lot of work and time wasting.
Perhaps if you explain your needs more accurately we can help better.
For what i understand you want to do , it is not possible and it wont work for a number of reasons i wont go in to now.
Cheers Damir