Turnbull? I have to correct ya on that. The scene where Mike was with Moe Green he mentions about the Molinari GFamily protecting Fredo. So in Both the Movie and the Novel Don Molinari was protecting the middle son.

MMFloors? I don't consider Al to be a button man position but more like a position higher than that. But there is no doubt that he supplies all the buttons of the Corleone Family, Ones that are left and he is Mike's right hand henchman