Biab a box should be able to do all this intelligently.

There are added notes and a chord in this video using PRT. These can also be used to add notes to existing RT chords once the PRT SFZ is matched to the same tone.
https://www.dropbox.com/s/ytk0n0rd5ziwpbv/RT3480-SFZ%5BSN0757%5D.mp4?dl=0

Same deal with midi, existing chord notes can be duplicated intelligently by Biab. This is all easily do in Reaper.
Midi Phrase Snap To Chord Tool