The most practical thing, IMO, is to use your arranger keyboard as a master keyboard and store in every performance memory the right program change number to be sent to your module for each song. I think that in the PSR 9000 this can be done storing the number either in the Music Database or in the OTS settings (but I am not sure about that). The 9000 pro has actually two midi outs and two different settings for master keyboard 1 and 2.