This is a tough one. I hate to nudge you onto a road where you may get hurt, but I will say that if I were in this position I think I would go for showing him the papers.
But I would do that near the beginning of the visit in case he has some reaction or is willing to talk about things. He may feel very awkward about walking in on your brother and you and doing nothing to help you, but the bottom line is you need some answers from him and have a right to ask for them.
The question, though, is this: Will you get those answers? Or will there just be an argument that leads you to further hurt and distress. As I don't know anything about your father I can't address these issues.
Normally I would suggest to a guy that he go for the small safe steps as opposed to the big risky ones. But this issue has been troubling you for a long time, hasn't it? Maybe it's time.
PS: I have been meaning to comment on the new avatar. Very nice! The photo is so beautiful and very relaxing.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)