Mary-Therese Tribbiani is one of Joey's sisters. She was portrayed by different actresses, Mimi Lieber on Friends and Christina Ricci on Joey.
On Friends[]
Mary-Therese
In "The One Where Chandler Can't Remember Which Sister", she has feelings for Chandler after Joey's birthday party and kisses him at a dinner at her parents' house. Chandler thinks she is Mary-Angela, and rejects her. Mary-Angela enters almost immediately after he asks Mary-Therese which one Mary-Angela is.
On Joey[]
In Joey, Mary-Therese has been renamed Mary-Theresa and has virtually no similarities to the Mary-Therese in Friends. She is Joey's second youngest sister and extremely spoiled. She is seen in only one episode, "Joey and the Fancy Sister".