Kate Rockwell, one of the finalists on the NBC reality TV series Grease - You're The One That I Want, is coming to Broadway, but not as a cast member of Grease. Rockwell is joining the cast of Broadway's Legally Blonde as Elle Woods's sorority sister, Margot. Legally Blonde will be further in the grip of reality TV fever next month, when the Broadway musical comedy's own reality series debuts on MTV.