3 party check

My Mom was in a car addident she was a passenger in my brothers car he did not have insurance, but it was not their fault. The other person was a fault and had min. insurance. My moms bills were around 35,000 which she is a seniore citizen and has Kaiser they have paid all bills. The problem that came up was she signed a waiver releasing them in return for the 15,000 insurance they had. When they wrote her the check they made it a 3 party check, to her Kaiser and Medicare. The release she signed was only for her and it did not say she was getting a 3 party check. What can we do? Can we send the check back and ask that they make it out to her? Help I don't know what to do. Maybe I can get a lawyer involved. I have no idea if Kaiser even knows. We did try to get them to change the release so pain & suffering only, they would not do it. Is this why they made it a 3 party check. I have never heard of this before. Trying to save lawyer money so my Mom got the full 15,000 she really deserved it She had fractured ribs and terrible bruseing on her stomach area. Has anyone ever heard of this happening before.
Thanks
Diana