I have very mild CP, while I work with a 22 year olf girl with severe spastic CP. I need an activity I could do with her. She loves to be out of her wheel chair.

Can anyone help me?

Have you thought about swimming? I work at a Camp for adults with disabilities and many of them loved the pool. Use a life jacket, or some other flotation device, and let her descide what to do. Things like sponges are fun to throw. Also if you can spin in circles it is a neat feeling that she probably can't get any other way. I hope this helps.
-Tink