Carla was the daughter of an Italian immigrant and impresario who often featured her in his shows, notably Senza Mamma. After the show, Don Fanucci threatened her in order to gain money from her father.
She was the sweetheart of Genco Abbandando and it is possible he married her later in life.
Behind the scenes[]
In The Family Corleone, Genco's wife is named Allegra. It could be that Carla was only her stage name and that she's the same person.