Well remember that Frankie "5 angels" was also added to the story as was several other characters. If you have the VHS version of the Godfather Trilogy, you may have the “A Look Back” behind the scenes commentary about the film The Godfather II and FFC tells us that most of the scenes of young Vito Corleone were from the book, but the story of Michael during the 50s was something he invented. So with that in mind there were several characters erected from this, including Frank Frankie Pentangeli, Hymon Roth, Johnny Ola, the Rosato and several other characters with smaller roles in the film.