Lily Potter did many things at Godric's Hollow; she forgave Severus, had a surprise second child, and she didn't tell anyone except Severus, the baby girl's godfather. After her death, Severus raised the baby girl as his own, keeping the promise he made to Lily, retain her safety. Now Poppy Lily Prince is at Hogwarts, where Severus can be a father and teacher at the same time.
Addie Blackwood-Potter didn't expect her first year at Hogwarts to be so dramatic. With not only you-know-who coming back but attempting to find her birth father, pushing for answers about the night her mother died, and figuring out her new school life at Hogwarts while being the youngest in her grade. Who says she can't have fun this year, though?