Changing bracket/braces pattern for staffs.

I have a piano score with the standard bracket spanning the treble and base staffs. I just discovered late in the piece that there is a second treble staff added because the left hand plays some notes on the bass and some notes on the treble as they are not scored on a common staff. The other treble staff is for the right hand. But for this section of the score, the two treble staffs are joined with a single bracket and not the traditional bracket as noted and the single bass staff has no bracket. I have not been able to figure out how to change the bracket pattern so it applies at the appropriate measure without removing anything from all measures in the score. Can bracket patterns be applied to only specific measures and how would I terminate the initial pattern, apply the new one, and then later return to the traditional display when I no longer need the extra staff. The image shows the first measure of the score with three staffs where the normal pattern has been interrupted. Also when editing the span of a bracket, it looks like I can only move down and not move the span to a "higher" staff if I try to modify an existing pattern.