They both do all 8 shows. Provided of course that they aren't sick. Patti has been a trouper while preforming with the hip issue might I add. In fact, a couple of weeks ago (before any announcement relating to closing was announced) the show went on hiatus so that Christine and Patti could take a break. While there were a couple of times understudies went on for each role, since the break they haven't called out. Highly doubt that they will now. Not just because it's closing soon, but, I can count the number of times each actresses respective understudy went on on less then one hand.