I am on ssdi, and receive a check for my 15 YO daughter. My daughter recently moved in with her father, and I lost primary custodial rights. Can I still receive the dependent's SSDI check, or does it go to the custodial father?

Did custody legally change though the courts, that is what I am reading here?

But no, the check is the child's, it goes to the custodial parent of the child to be used for the child.