I like the idea of having to leave grandma's because she wet her pants. I might have to use that one -- thanks for the tip.
Today, we're giving the underwear a rest. Everyone involved was getting frustrated and it didn't help that DMIL has been telling me to back off -- she watches DD two times a week and doesn't exactly stick to the routine I've set up at home, much to my dismay. "I've raised 4 boys!" she says. I think it's fabulous she's raised 4 children, but she hasn't raised mine! DD is WAY different than her boys, even she admits. Can you tell I harbor some bad feelings about this?
I leave in about a week for a 5-day out-of-state trip for work, so I think I will start it back up in a couple of weeks. Give DD a chance to cool down with no pressure. And give my DH a break the week I'm gone!
Thanks for everyone's advice. If you have any other ideas, I'd love to hear them. This potty business is the pits!