I dont want to seem like I'm being selfish or anything but I have planned a week long vacation at WDW. I am taking my Fiancee and her parents to WDW and I'm paying for everything. I have spent months planning and yesterday I find out that they would like to take a day and go visit some people in the area. Now we dont have a car so this is not going to be easy and to top it all off these people live 3 hours away. I have planned dinners and have the dining plan and have planned everything to make it a great vacation. My Fiancee tells me that she is going with them but I dont have to go. Sure, I dont have to go. How is that going to look. I dont know what to do now. Best of all, they dont know which day they are going to go so I have no idea what to change.
Ugh...what to do
Ugh...what to do
I am just a little tense about having to replan everything at the last minute and worry about how we are going to take this side trip without a car. They do not expect me to pay for any other expenses including a car. They would pay for all of that. I just dont want to take an entire day out of the schedule for this. Especially if I dont know when it will be

got to admit i edited my post after i heard the inlaws in question were reasonable...I have a child with similar problems as yours and it seems it just gets worse over time...i feel for you!
(mind you when they come up north they can't find the time to visit her!) It is very aggravating when you plan a DISNEY vacation and she expects us to rent a car and cart her everywhere she wants to visit. We have suggested that they come pick her up at the hotel but she feels that is not right. Don't get me wrong, I love my MIL dearly but some times she can really get on my nerves.
I would strongly suggest to your future inlaws that they have their friends come visit them at Disney, seeing that you are paying for their trip. Good luck in whatever you decide to do.