This bug might have been already discovered, but whatever. 
First, you'll need to do all the jobs for Salvatore. And then do the jobs for BJ Mordino, until he wants you to kill Salvatore. Go to the bar, and steal Salvatore's oxygen tank and get out of there before the Salvatore's turn hostile to you and return to Mordino.
And there you have it, you're an Made Man of the both families!
First, you'll need to do all the jobs for Salvatore. And then do the jobs for BJ Mordino, until he wants you to kill Salvatore. Go to the bar, and steal Salvatore's oxygen tank and get out of there before the Salvatore's turn hostile to you and return to Mordino.
And there you have it, you're an Made Man of the both families!
