She was born some time after Johnny Sack's incarceration in 2004 and before 2006. Her parents are Bobby Baccalieri, Jr. and Janice Soprano. Domenica enjoyed the festivities of the "Feast of St. Elzear" in 2006, when she was already tentatively walking. She was involved in the ride malfunction but did not seem upset and enjoyed the attentions of her uncle, who spun her around in the air. She was seen older at her father's lake house, when her Aunt Carmela and Uncle Tony came for Tony's birthday. By this point, Nica was openly defying her mother's authority, a course of action which almost provokes Janice to violence.
After Bobby's murder, Janice declares her determination to keep Sophia around because Nica adores her big sister, but shows little or no interest in what is to become of Bobby III.