I would love to send a MIDI track to multiple instruments (VST or external). I know you can duplicate a track easily enough but then you have an editing problem keeping them synchronized. I suspect this requires the concept of "patch points" or AUX tracks for MIDI - you'd create a new patch destination for your MIDI track, then select it as an input for two or more MIDI or Instrument tracks. I guess you'd need to prevent a MIDI track from both sending and receiving from the same PatchP