TVLand had already scooped up the illimitable Sutton Foster to star in Younger, a comedy from SATC’s Darren Star about Liza, a 40-something single mom who reinvents herself as a 29-year-old at work. Now Hilary Duff has joined the cast as Kelsey, a 20-something friend of Liza unaware of their age difference, and who, if she learned the truth, would surely recoil from Liza as Nosferatu would from the burning light of day.