You should be able to split your keyboard to play arranger chords/melody/keyswithches using JS MIDI Keyboard Splitter, with Xackley Zero Tricks.
So insert a track under MIDI Chord Input track,
drag the ROUTE from track 2 onto track 1 ROUTE,
enable the keyboard input from track 1 to track 2,
arm to record and record monitor ON.
You can drag another ROUTE from Track 2 to a Virtual Instrument track that will play your melody/lead sending all channels or a particular channel that is set in the Keyboard splitter.

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