Do many people use custom scales? If not, or perhaps also, the custom scale interface could be used to create custom chords. Within limits obviously.

Then is addition to 1,100,200 etc chord settings could be user1 user 2, 3 and 4, one for each row or more if you use banks.

organised by MIDI notes. 0 as base note, then turns to the right for + notes, and turns to the left for – notes. Each encoder turned is a new note added.