News Corp. prince Lachlan Murdoch is no longer on the hook for the $15,000 monthly rent at the Laight Street loft he abruptly vacated in August after a series of power spats with his dad, Rupert. Lachlan and his wife, Sarah, were living in the 3,555-square-foot pad, with double-height ceilings and three exposures, while slowly renovating the mysterious $5 million building they bought at 11 Spring Street (they got a permit to gut it in 2003). The couple’s move back to Australia scuttled that project, along with his status as Dad’s heir presumptive. Lachlan’s landlord, tech mogul Kirk Loevner, put the loft on the rental market with Corcoran’s Bill Kowalczuk, who found another international scion to move in: Valerio Morabito. He’s an Italian playboy whose family fortune comes from construction. He might be best known for investing in the Fashion Café restaurant chain (hawked by Naomi Campbell and Elle MacPherson) and then suing founder Tommaso Buti after it went belly-up. (The two settled out of court.) Next: Robert Morgenthau Gets Witchy