529 owned by a grandparent..does the beneficiary child have any "rights" to the money?

It sounds like your father is dead broke. If he wiped out his retirement savings, how is he going to afford a CPA? I think you need to come to terms with the inevitability that your student will see none of that money for college. Your bigger concerns would be how you can avoid financially supporting him and his wife when that 529 money runs out, and how you can replace that money in terms of helping your child with college expenses. It is a very sad situation.