A. Legitimate dilemma, but only if his father/brother-in-law-to-be are firmly against gang-railing the shit out of hookers.
If there is 100% no way he can tell them to f*ck off you have two options to get around them being there or having a joint co-gender gathering of yawns.
The first line of defense to get around including pops-to-be and the prudish Bro is plan the initial party somewhere expensive or at inconvenient time. I suggest a mid-week time-slot and a flight somewhere. Best case scenario: Her brother won’t be able to take off work, and the father has a weak heart or some other health defect that keeps him grounded. (If you're forced into keeping it local, with family in tow, make sure the Dad is picking up the whole thing — steak dinner, sports tickets, etc.)
But maybe you can’t shake them no matter what. Or maybe ditching them isn’t even the issue at all. Suppose your friend's future bride just wants the parties to be together. It’s all too plausible and second nature for some chicks to be terrible like this. In this instance, there is only one solution that will allow you to avoid both. And it doesn’t include fire-bombing this chick's house.
You throw this f*cker you call a friend a second, very discrete bachelor party in an undisclosed location. It’s going to take a lot of planning, lying, and possibly a human abduction followed by all-cash transactions, but you can pull it off.
If you and all your close friends have girlfriends and they all love each other like “besties” often do, the series of lies cannot all be the same. One or two guys needs to be going away “on a work trip,” another needs a “dying aunt” several states away, and so on down the line. That is, until you get to the friend you like the least. He has to stay behind to remove all suspicion of this double-secret bach party. Tough shit for him, but he's practically invisible anyway.
In the ideal event that your friend who is the bachelor is the only bozo in a relationship, just make sure he has a bulletproof excuse/alibi. Work trips or conferences are probably the best bet. And whatever you do, bring him back in one piece (on the outside anyway) otherwise the ice princess will never let him see the light of day again. Just make sure you don't post the photos on Facebook or tell the friend you left behind. That guy sucks anyway.