Peri Gilpin, Nia Vardalos

Nia Vardalos and Peri Gilpin will guest-star as bickering sisters on an upcoming episode of Grey's Anatomy, according to The Hollywood Reporter

Vardalos, who wrote and starred in the hit comedy My Big Fat Greek Wedding, has recently appeared on Cougar Town and Drop Dead Diva. Gilpin, who played Kelsey Grammer's sidekick on Frasier, currently co-stars on the ABC Family series Make It or Break It.

The pair's episode is schedule to air mid-January.