All members of the family? You mean like 350-400 made guys in one place when the mob was in its heyday? That's the movies, and a bad movie at that.
I found
The Apalachin Meeting (1957) by Albert Hitchcock a very believable movie. All the bosses and their closest lieutenants and major heroin dealers as well as reps from Sicily coming together to eat steak and make major decisions that would determine the mob's future during their heyday. I thought it was pretty realistic, but then again it was just a movie.
