You can rent a wheelchair for your length of stay at Disney, its cheaper. They do have complimentary wheelchairs for guests to get from the transportation drop off point to the main gate of the theme park.
Disney Resorts also offer complimentary wheelchairs but its as available and honestly some of them are in really bad shape. My dh tried to fix one with a castmembers tools in the Beach Club Lobby once. That is when we decided to rent one ourselves.
We rent from an offsite company, Randys Mobility. I like their policy of not charging an insurance fee for if the wheelchair gets stolen etc.
They drop off and pick up right where you are staying so its so convenient.
If she is in the wheelchair you can also view the parades and fireworks etc. from the designated wheelchair viewing areas in each theme park. You can view the map for location or ask the cast member etc.
Wishing your dd all the best.