So, I might have a song with the notes: C, E, G. I want BIAB to develop a function that will change them from C, E, G to something like this (imagine the following notes stacked on a stave on a sheet of music):
G, C, E
E, G, B
C, E, G.
The bottom C being C4. This is a simplistic representation, and it is just adding to the original single notes to produce a fuller melody sound.
What you describe above is exactly what the MIDI Harmony button does that I mentioned in my above post. Harmony can be generated using the button and then that harmony can be written to the melody track to create the blocks of chords that you describe. In what way does this not do the job for you?
The image on the left (below) shows the melody before I wrote the harmony to the track. The image on the right shows the block chords after I've told BIAB to write the harmony to the Melody track. (I've used Nashville Piano (3 part) harmony.)