I can relate to your post Lori (pirateofthecarolinas)! The first week of June we were supposed to go to the beach, DH, myself, and our 2 ds's. Back if Feb when I made the reservations, DH asked his parents if they wanted to go too, since the house we booked had 4 bedrooms, and we only needed two. They said they'd think about it and let us know, no big deal.
The day before we were supposed to leave, we had to cancel because of a problem at DH work. I called MIL to see if they still wanted the house, I could pay $75 to have it transferred (less than 24 hours before checkin was the reason for the fee) and save having to cancel it and lose the money. SHE DIDN'T KNOW YET IF THEY WERE GOING! Hello!?!
She thought it would be fun to go to Disney with us, and as much as I really do like and love my IL's, NO WAY! I told DH, and he agreed. If they would happen to go (WDW is a free place, I can't stop them, lol), they can't eat with us because they won't decide to go until 2 days before, and I'm not fooling with that!
Please don't let it stress you too bad! I ran the scenario of all the horrible things that would happen if they did go through my head for hours and lost 2 nights of sleep over it almost.