In Season 3, Greta first appeared in Phan-Tom Of The Oompah, and her identity looks like Nibbles Mouse and Rutger, Rolf, and Rudy, but with blonde curly hair, and a burgundy colored dress. In Season 4, her next appearance is Maust.
She is also Jerry Van Mouseling's love interest. (Jerry's third love interest, not to be confused with Olive.)
She also appears to be the daughter of Papa.