My brother refuses to pay for my daughter's medical bills?

Sue him. If he is extremely wealthy and not offering to pay for that he is not much of a brother at all and if he refuses to talk to you again, it is no big loss. You can check to see if perhaps he has some type of insurance that would cover that or perhaps you may have something in your own home insurance as well to cover it. It could also be that even if you do sue, he has some type of insurance that would pay that so it wouldn't cost him anything other than perhaps higher insurance payments in the future.