The Rosato crime family was formed by Tony Rosato and Carmine Rosato after Frank Pentangeli refused to grant them territories they claimed were owed to them by Peter Clemenza. They were backed by Hyman Roth in Miami.
The family was split into two factions, Tony Rosato's family and Carmine Rosato's family. Tony took over several construction and a drug and a gambling rackets and three fronts in Florida while Carmine seized several prostitution, and a drug rackets and three fronts in New York.
Behind the scenes
The Rosato family only appears in the video game. In The Godfather Part II they form a rogue faction rather than having their own family.