If this is a casual gathering then it wouldn't surprise me to see a son or nephew or something to that affect there. It doesn't appear to be an Outfit-exclusive gathering. It's very possible that some of these guys are civilians. Also, it looks like some women (wives/girlfriends?) are in the background although it's not known if they are with Accardo and friends. If they were, it would not be out of the ordinary for the times to have the men together on one side and the women together on another.
The location could also be a clue; Fosco stated that the location that it was somewhere to the northwest of Chicago (can't remember his exact statement) and Amato and Potenza - two guys who operated out of that area for the Outfit - are apparently present. Maybe some of the guys are operatives out of that area who don't have existing photos.
I think this is something we're all taking for granted. Good chance some of these guys simply won't be identifiable because they aren't known or are civilians.
Sam Destefano was, without a doubt, made. Snakes is correct, its an urban legend that he was not. I think there's a very good chance that sunglasses is Mario.
