Help!

I've done a ton of long-haul flights with just DD#1, and a few short ones with both girls while DD#1 was still in diapers. At Easter I'm going to have to do one leg of our trip alone with both girls (11 months & 2.75 yrs). The problem? DD#1 is fairly newly potty trained, and it's a small plane with what I'm assuming will be TINY bathrooms. I'm not even sure we could all fit in it together!

Has anyone flown alone with two little ones, one who is newly potty trained? Any tips? It SHOULD only be a two hour flight if we take off on time, so I'm hoping she won't even have to go, but want to be prepared and would hate for her to have an accident, particularly involving poop since it would be virtually impossible to clean up in the bathroom with the baby strapped to me.

We don't normally do pull ups when we go out, so she doesn't know what they are...I'm considering telling her they are "special undies" and using one in this circumstance, but would hate to set her back in her training.