May be of some help
branwyn,
I don't know if it would be helpful to your or not but I am currently reading a book called Drugs, Drunks and Debits. It's written by a Certified Financial Planner who lived with and loved an addidt. He talks about his lessons learned and offers help to protect those that aren't sure how to protect themselves (both emotionally, physically and financially).
I purchased the book because our library system didn't carry it. I'm in the early stages of the book so I haven't reached the part where this Financial Planner talks about protecting a person's assets.
Go to dub dub dub dot preventragedy.com if you want to research it more.
I imagine it won't be helpful seeing your father hasn't hit HIS bottom yet and is still enabling your mother. But maybe, just maybe there will be something in there that will help your father.
I'll keep reading and report back if I read something I feel will be of help.
Sorry you find yourself in the situation you are in. I have an A-BIL (brother-in-law). They have no children (whew) but still my W and I will be on the hook to help bail out my W's sister once her H hits bottom. He's already racked up $14k in debt ... and neither of them has a high paying job. This is why I'm reading the book.
Good luck and try to take care of yourself.