Melissa Joan Hart's sister might join her in the TV-star business.

Melissa stars as Sabrina on The WB's hit series "Sabrina The Teenage Witch". Her 15-year-old sister, Emily Hart, will be on the show this Friday in a role that could possibly spin-off into a new series, zap2it.com reports.

Emily will play Sabrina's bad-news witch cousin Amanda who goes to live with Sabrina's aunts, Hilda and Zelda. Sabrina must then try to get Amanda admitted to Witchright hall, a school for difficult and "magically challenged" witches.

"There are supposed to be lessons," Melissa told zap2it, "but it's also very funny. Emily's got this great sense of humour and this kind of dry sarcasm that I think comes from my father. She uses it really well, so that's the way the character is. She's just this troublemaker - 'I don't care. I'm going to do my nails.' She's snotty and evil."