Terry, I'm not sure this will help with what you are trying to do, but the TYROS also has a full keyboard mode. Playing in that mode, the "chord" can be triggered by a combination of notes in the left and right hand. In fact, the right hand alone can play the chord. When playing in this mode the chord only changes when three or more keys are pressed simultaneously. If you are playing single notes, in either hand, the chord remains set at whatever it is. Of course, for the harmony, you do need to produce a chord.