Kari,
what you are asking for can be done for sure in a dedicated master keyboard or you could use a midi patch bay: I have one of them, amd basically it's a module with 8 midi ins and 8 midi outs and a memory bank where you can store a lot a data for each program, like program change numbers to be sent to each midi out for every program, split point, transpositions, etc.
I have checked the 9000 pro manual and it says that the only difference between Master Kbd1 and Master Kbd2 is that the second does not transmit aftertouch data. The manual mentions also the possibility of enabling/ disabling the transmission of program change numbers for both the upper and lower part, so I think that it could be possibile to match the voices of the pro with the voices of an external module. I still think, however, that a midi patch bay could me a more practical, powerful and rather inexpensive way to solve your problem.