I want to first tell you I know exactly how you feel.
There is a image one gets about a family trip to Disney World or any family vacation for that matter.
I for one am the expert planner. Everything is set in my mind and then on paper. The reservations are made, which days will be spent where, how many hours at the pool. I mean I plan everything. Its sickness really.lol
With that said, our last trip was overplanned. We usually go every 2 years but our trip 3 years ago was canceled due to illness.
Fast forward to last years trip. When I say we were looking forward to it, that would be a huge understatment. Everyone was involved in the planning a this trip couldn't come fast enough for anyone.
When my parents declared 2 weeks out that they wanted to join us, I was happy about the idea of this time for my children to spend with my folks but part of me felt like it was going to be an invasion somehow.
Then when I was told that my uncle, aunt, cousin and her 2 children were meeting us there on arrival day, to say I was freaking out doesn't even cut it.
We already had all of ADR's, what if they couldn't get the same hotel?
How are they going to keep up with us? What will they do when we are at dinner? What if they don't get the same flights as us? How are we going to see and do everything with all these people just deciding at the last minute to join our families vacatioin?
After all my stressing out and being determined not to let anyone spoil our time in the end it all worked out fine. Not exactly as I had planned it mind you but it worked out.
I made sure we seen and did everything we plan too.
I even went so far as to leave my relative back at the hotel so we could stick to our original plan.
My uncle passed away 4 months after that trip.
He was my favorite uncle, always there for me as a kid, my god father, and just an awesome guy. I miss him dearly and not a day goes by that I don't wish I would have put my plans to the side and just relaxed and spent more time with him.
Just something to think about.
Disney is not going anywhere anytime soon. With any luck, hard work, and determination if you love it that much you will get to go back again & again with your children.
People on the other hand will not always be there.
Allow them to throw a rench in your plans if they should, go with the flow while they are with you, make the most out of it and then cover all the rest when they leave.
Your MIL is coming to help you and spend time with your little one's, she sounds like someone worth spending time with. I know how you are feeling about the special time with your own family but your kids are blessed to have not only their parents but their grandmother & aunt their too.
Relax, take a deep breath, and enjoy the magical place on earth with people who you love and love. In the end thats what DW is all about after all.