People keep saying she’s not confirmed to be Celestia’s daughter, but she also sells food to Celestia off hours and with a huge discount in one of the shorts, so they canonically have a very good relationship with each other.
A Younger-Self Principal Celestia or a Daughter Principal Celestia?
Neither. This character is Summer Solstice. While she does resemble Principal Celestia, the Equestria Girls series doesn’t confirm that Principal Celestia has a daughter.
It’s my daughter I had with Celestia :p