Just to wrap things up. I tried calling WoH line, and the agent was unhelpful. Wanted to reprice and rebook the entire stay as one 7 day reservation, where the final price would've been an increase of ~60% over the rates I've already secured.

Tried calling the property directly to try to merge the reservations, but they weren't willing to touch it (as many here have advised).

Ended up not wanting to play the HUCA game with WoH line, and just used up 2 certificates instead of one.