The series, based on the novels by Sara Shepard, will focus on twin sisters Emma and Sutton (both played by Alexandra Chando), who run into trouble when they decide to switch identities.
Pasdar will play the father of Sutton's best friend Madeleine (Alice Greczyn), according to TV Guide.
The actor played Nathan Petrelli on NBC's Heroes from 2006 to 2010, and has also appeared in recurring roles on Castle and Desperate Housewives.
His film roles include 1987 horror Near Dark and 1993's Carlito's Way.
Andy Buckley and Helen Slater previously signed up to play Sutton's adoptive parents in The Lying Game.
The series will premiere on August 15 at 9/8c on ABC Family.
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