OP here. Sorry to raise everybody's blood pressure, but nice to know that I'm not a brat for feeling like I've been run over.
Called my MIL this morning and told her that if they wanted to come down, they could do so AFTER my mom and sister left so there would be no overlapping. But I told her we would only be able to extend our vacation by 2 days. I also brought up the fact that we would be going in December and they might have to potentially drive down in the ice and snow. We're supposed to drive up to Nashville in a few weeks to meet with them (they're driving over from IL) and I told her I would rather just make it a 2 or 3 day event than driving up for just the day, which is what she originally wanted to do. "I think it's important that the kids get to see you, but Disney isn't the place to do so. We've had this vacation planned since August and I don't think you'd be able to keep up with us and do everything that we want to do."
She didn't like it, but I stuck to my guns. I even suggested going to Disney this summer or Fall with the kids if she had her heart set on Disney, but she said she didn't think they would be up for that.Guess she only wants to go when it's inconvenient for me.
Glad that the trip is back to it's original schedule. DH couldn't believed I called her, but thinks it's for the best too.
Way to go! Tell DH he owes you big time he should have never let it come to this.
You handled that GREAT!
You deserve your trip, and even though DH probably should've manned up a little bit and done the job himself, there isn't much that can stand in the way of a determined mother, am I right?! I always tell DH, while our kids are young (DS is only 1) we're the ones that are responsible for standing up for them because they don't have the opportunity or capacity yet to do so and it seems like you pulled through for your kids. 
