The person who played Herb Melnick’s sister is Judy Greer. Born Judith Therese Evans on July 20, 1975 in Detroit, Michigan. She is best known as Judy Greer who starred in films such as What Women Want in 2000, The Wedding Planner in 2001, 13 Going on 30 in 20014, 27 Dresses in 2008, Love & Other Drugs in 2010, The Descendants in 2011, Carrie in 2013, Jurassic World and Ant-Man in 2015.
It was in 2007 when she first appeared on the episode Smooth as a Ken Doll in the fourth season of Two and a Half Men wherein she portrayed Myra Melnick, Herb’s younger sister. This was the only episode wherein Myra appeared and although Judy Greer went back on the show during the 9th season, she portrayed a different character.