Gossip Girl producers, writers, and casting directors really went all the way to make the White Party scene from the episode they’re currently shooting as authentic as a New York society party could possible be. Proof? They brought in actress, designer (of Samantha Thavasa handbangs) , and Manhattan’s premier young socialite Tinsley Mortimer to star in the scene. And Tinsley was nice enough to bring her young sister, Dabney Mercer, onto the set with her. Oh, to be the sister of the most famous socialite on the scene right now…

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