Another related note to schedule changes: If ticketed by JL, and AA has a schedule change on a domestic US segment, how easy/difficult is it to change that to a flight of your choosing rather than cancelling?

From what I read here, cancelling a partially used ticket due to schedule changes is more lenient with JL then AA, but if I want to keep the trip but change the flight, I've found sometimes tickets by partners are harder for the operating carrier to change. Sorry if this was discussed already, as I didn't see it mentioned.