STEPHANIE Winston Wolkoff is not a granddaughter of jeweler Harry Winston, as we reported here last week. Wolkoff — who just quit as Vogue’s head of special events to spend more time with her husband and three kids — was adopted by Bruce Winston, one of Harry Winston’s two sons, when Bruce married Stephanie’s mother. “Harry Winston has only one true grandchild, a son born to Ronald Winston and his wife,” a family source says. A rep for Wolkoff said, “In New York state law, an adopted child is treated the same as a natural- born child.” Bruce told us, “If my father was alive, I’m sure he would be proud to call her his granddaughter.”