A brother of New York Sen. Hillary Clinton and local Democrats who backed her unsuccessful presidential campaign socialized privately Monday with a top surrogate of the presumptive Republican presidential nominee, Arizona Sen. John McCain. The private gathering featured Carly Fiorina, Mr. McCain’s top economic adviser, and took place at the Dunmore home of political consultant Jamie Brazil, a longtime friend of Mrs. Clinton’s family who has signed on as paid national director of Mr. McCain’s Citizens for McCain Coalition. The attendees included Tony Rodham, Mrs. Clinton’s youngest sibling, his wife, Megan, and their two children; attorney Kathleen Granahan Kane, who...