I can only tell you what I know (not much! LOL!). My DD has cerebral palsy and her physical therapist nominated her last year for a wish through Make A Wish. I had always thought it was for kids with cancer or that kind of thing. But because of my DD's disabilities (she has a shunt, a feeding tube, a baclofen pump for spasticity) and potential risks of surgeries and things like that, she was eligible. All I know is she was nominated and the doctors agreed she was eligible. Anyone can nominate someone and then it's the child's doctor who decides if they are eligible, from what I understand. In my DD's case, her PT sent a letter to her neurosurgeon. I hope that answers your question.
BTW, we went on her trip in November and January 7 we rushed her to the emergency room and she was in the hospital for 6 weeks! Came home on I.V. nutrition for 3 months, went back for surgery and was in for almost another month. Never before has she been hospitalized for illness. It was scary, we were thinking maybe that was our last vacation together as a family. But thank God, she is doing much better.