Alvin and the Chipmunks (TV series)Edit
Although the fact of how she ended up at the orphanage is unknown, we do know that she took the Chipettes in when they were just infants. While they became close as sisters, she kept them hidden from the rest of the orphans in fear that they'd use her friends' musical talent for their own benefits.
That is, until the Chipettes were discovered by Eva, who threatened to expose them if Olivia didn't give her her mother's old bracelet. This event had led to her friends to steal back the bracelet after seeing how sad she had become. But, in the process, they were caught by Miss Grudge and after she threatened them, she hid them inside one of the orphanage's vents.
When Olivia was finally adopted, she went into tears after Miss Grudge lied that the Chipettes ran away and that she would have to move on.
Years later, she would reunite with the girls at one of their concerts where they shared a sisterly hug after it was over. Soon they would tell their side of the story of what happened to them at the orphanage. Soon after the girls are done with their story, they, along with Olivia, would go over to the Chipmunks house for a party prepared for the Chipettes, and after a talk, Alvin begins to tell Olivia all the great things about himself (after he had seen what a beauty she had become and after she said that she was a big fan of his), to which the others just found annoying.