She needs to be out of the bed sometime in the day. But no one gets her out because she "wants to go back to the bed after 10 minutes". This can't be a new problem where she is not comfortable in the wheel chair. She also has control of her bladder so she could go to a bathroom, but they keep her in diapers. If she is slow on choosing what she wants to eat, she is given a peanut butter and jelly sandwich. She was recently in the emergency for dehydration. Someone should give her some water every couple hours.
If she really wants to be in bed that much, she may be depressed - wanting to stay in a cocoon. Is she new to the nursing home?
She needs to get out of bed, and into the world as much as possible.
I would contact the therapy department and find out if she is getting PT, how often, and if they can evaluate her wheelchair for comfort.
You know they can't make her do. Its easier just to let the patient have their way then try to talk them into something. And God, I hope I never am put in a wheelchair for the whole day. I am a lounger.
Can you get a care meeting together. Find out what the problem is. Maybe she needs to be transferred to a facility who can work with her problem. A person who is continent should not be made to wear a diaper. She should be taken to a bathroom every two hours.