Hi, Becky! First of all, let me tell you how much I admire you for caring for your daughter in such a noble and compassionate way. My mother also has similar disabilities, and we have to look for ways to maintain her dignity yet keep her in good care. After taking an extensive tour of the First Aid Station at the Magic Kingdom and meeting the kind and caring attendants there, I think that you and your daughter would be welcomed (as well as the other parks' First Aid Areas) as long as there isn't an emergency situation being handled.
On a lighter note, I am always overwhelmed by the reception my mother receives at WDW. Most recently, we were waiting for Mickey's Jammin' Jungle Parade to begin at Animal Kingdom, and I had "parked" my mom in her chair in the designated area for guests in wheelchairs. However, as the crowd gathered, some able-bodied guests (mainly children) stood in front of her blocking her view of the parade -- which she didn't mind one bit. Yet, as Goofy walked by, he could see over the children's heads and pantomimed for them to part so that he could see my mom. When the children moved, he held his arms open wide for a hug as she copied his gesture. I was standing far enough away to capture the moment on my camera, and I cry every time I remember it. My hope and prayer is that you, your daughter and every guest experience how special she felt at that moment!
Please let me know if you have further questions. I sincerely hope you have a wonderful day and a magical vacation full of precious family moments!