Relatives of the late William Gottlieb continue to feud over his extensive estate, which may be worth more than $1 billion. The real estate mogul’s properties include 150 historic buildings in the West Village, Greenwich Village and Chelsea, including the Keller Hotel, the Northern Dispensary and the New Holland Hotel. Gottlieb’s grand-nephew, Michael Corbett, says he was promised a one-quarter share of the estate by his grandmother, Gottlieb’s sister, Mollie. When her final will was revealed after her death in July 2007, however, Michael had been cut out, leaving Neil Bender, Mollie’s son, as the sole beneficiary. Corbett says Bender cheated him, his mother, and Mollie’s other grandchild out of their inheritance, which was supposed to split into four equal parts, according to a previous will. The case, which seeks to overturn a previous decision by a Manhattan Surrogate Court judge, will be argued in appellate court tomorrow.