If you don't want an instrument to regenerate with the others Freeze the track/instruments. However, if you make a Chord change with frozen track/instrument the chord change will not effect that track. You can change a C7 to a C9 freeze the piano, Drums and Bass leave the guitar unfrozen that will sound OK. But if you change a C to an F that will not sound at all correct. Look up substitution chords and you can see what chord changes you may try making for only one instrument while others are frozen.
I freeze the drum track when I like the sound of the drums.

I also freeze my guitar/piano track when I change a C to a C/G(or Cmaj with a G Bass that is what this notation represents) C/B, C/A and I only want the BASS to pick up the change. I'll make a series of slash chords after freezing the Guitar track (or piano) and then regenerate the Bass. The bass pattern follows the bass notes indicated in the cord, most of the time. The Guitar and/or the Piano stay on the basic chord.

"When you help somebody else you are really helping yourself"