Hi Ron
don't know the montage, but years ago I used to have my PSR 1500 midied to my clavinova ( mine is a straight piano no styles).
I only had a single pedal, so changing variations didn't work too well, I still needed access to the buttons.
Also had it midied up to band in a box software, where band in a box played the chords, the PSR followed the chord changes.
Basically a case matching up the 2 midi channels.
Midi out on your montage channel has to match "midi chord detect channel "on your t4.
It's way too long ago for me to remember exactly what I did and there would have been other settings especially for my biab setup as it included syncing clocks.
But should be doable, if all you want is chord changes.
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best wishes
Rikki 🧸
Korg PA5X 88 note
SX900
Band in a Box 2022