Yep, not enough points for the additional top-ups. I also want to get a 35K cert back since I'll only stay two nights, but alas, none of those situations will help me. In the end I've decided to just cancel the entire reservation and rebook somewhere else.

It's just frustrating that Marriott's reservation system doesn't let you just drop a award night without changing the remaining nights, and so you're forced to make individual one-night reservations. The IT could definitely use an upgrade.