Hi, Julie!
I am so excited for your upcoming trip. It will be here before you know it!
Each queue is unique, so you will need to ask the cast member at the entrance to each attraction whether or not your mother in law will be able to wait with you and if the
attraction is accessible with a wheelchair. Some queues are accessible, some are not. Also, if she stays with you and needs assistance (pushing her wheelchair) then someone in your party might have to stay with her.
If she decides she wants to ride with the family, you will again have to ask at each attraction as for many of them she would need to transfer, and for other attractions she can stay seated in her wheelchair. It all depends on the nature of the ride, attraction, or show.
If you are staying at a Disney resort, you will find that resort
transportation is able to accommodate
guests in wheelchairs. If you need an
accessible room, make sure to make that request as soon as possible. The number of accessible rooms is limited at each resort so you want to make sure all her needs are met.
Wishing you a magical vacation! I am sure it will be full of magic!
Cathy