Provenance: Australia Ages: Katherine, 29 (left); Alexandra, 25 Home base: The sisters have places in Sydney and New York’s SoHo. Daddy: Down Under’s former prime minister Paul Keating Social cred: Trip to Cannes last May; Boom Boom Room membership; Sydney red-carpet appearances galore Claim to fame: The duo were André Balazs’s escorts to the Standard’s Halloween party last October. Dressed in elaborate custom-made Black Swan–inspired regalia, they silently followed the hotelier around the 18th floor while Marion Cotillard and Liv Tyler admired their feathers. Secret weapon: Brains. Katherine’s political consulting firm has advised business tycoons; Alexandra was CEO of GoFundraise, an online charity venture, until 2008.