My AH is addicted to Oxy's too. He just had surgery last week so I'm afraid that we are going to be back to square one. The brain will want more after just a little taste. He's looking into methadone. It's apparently not as user-friendly as suboxone but it's cheaper. He's been on it before and hated it so if he's seriously looking into it again, it must be bad.
I wish you luck! Good choice letting your Dad hold the pills. I hope the weaning helps and keeps the withdrawals to a minimum.