Thanks for your help on this. It isn't so much an issue of someone keeping him from me as it is, he has disowned my dad and by extension, me. He won't talk to/help me, and no one involved will either since they're all renting his basement and can't lose that.
I appreciate the info for everyone else, though, and perhaps after he passes away I'll be able to continue my search for his lineage. But as it stands, I've kinda (I think) run into a wall with this line.