Hi-
I am sorry I have been off the boards a lot because of the flu but just saw your question. My mother uses a wheel chair and we sailed on the October Wonder last year and will be sailing on the October 25 Magic this year all together.
I would suggest bringing a wheel chair that folds. At night or when not in use my Dad folded it in the hallway and brought a little lock and chain. I am not trying to make you paranoid but some man try to take her chair which is the one she uses at home not a rental and said it was nicer than his
We found the elevators small so you may have to wait until you get a empty one. People can be very inconsiderate of the wheel chair users and pushers too so be agressive if needed. It is amazing how many people will push and shove and have rude behavior this did happen on the ship but was much worse at WDW.
At dinner you can wheel your MIL to the table and then the server will take the chair out of your way and bring it back when done, that is for any meal.
At the shows they reserve the last rows for the handicapped and their traveling campions.
At check in make sure the CM checking you in knows you are traveling with someone in a wheel chair and they will direct you to the front of the terminal to wait for boarding so you don't wait in line and then a CM will come and get you for boarding before anyone else.
At
Castaway Cay they have sand wheel chairs. You can take the tram to the drop off for the sand wheel chairs. One word of warning the chairs are great for the hard sand and shallow water but VERY hard to push in soft sand. This time my MIL is going and my DH has to stay home (Marine) and he helped my Dad who could not push in the soft sand. I think we may carry her to a chair and use the sand wheel chair for her to go down to the water.
If I left anything out please ask away.
Have fun.
Tiff