Gia Giudice has reportedly been playing substitute mom at the Giudice household.

The 14-year-old is older sister to 9-year-old Milania, 8-year-old Gabriella and 3-year-old Audriana, and has been caring for her siblings since mother Teresa Giudice entered prison January 5 in Danbury, Conn.

"Teresa and Gia have always had more of a friendship than a traditional mother-daughter relationship," a source told RadarOnline. "Gia is stepping into the mother role. It comes naturally since even when Teresa was around Gia was frequently responsible for disciplining her siblings."

Teresa and husband Joe Giudice were sentenced to 15 and 41 months in prison, respectively, on multiple counts of fraud in October 2014. The pair will serve their terms separately on account of their children, with Teresa to be released early in February 2016.

Gia visited Teresa in prison for the first time this week with her father and sisters. A source told E! News the teenager and her family "were amazed at how good [Teresa] looks" and "were impressed at how nice [the prison grounds] are."

Teresa previously revealed Gia had offered to help her father with her sisters on Watch What Happens Live. The 14-year-old declared she is certain her family will be "better than ever" after her parents finish their sentences in a subsequent interview with Access Hollywood.