Thanks Manuel but my setup is already too complex and all the Midi connectors and USB's ins/outs are busy in most of my keyboards. I thought the easiest way was to program each instrument, for example the registrations in the PSR, the STS or Performances in the PA and the Programs and combinations in the TR in a the desired sequence so by pressing the foot switch it would change to the next sounds and/or style variation in them all simultaneously.
However I will read more about a Midi Patch bay but I guess adding it would force me to rethink the whole configuration of the connections I already have.