Soprano Aprile Millo — who’s singing Nov. 17 at Frederick P. Rose Hall at Time Warner Center — has friends in places as high as her golden voice. In honor of her 25th year with the Opera Orchestra of New York, Princess Verne of Rajpipla (India) is throwing her a cocktail party with such guests as director Franco Zeffirelli and his son, Pippo; Piero Slim, from the richest family in Mexico; Spanish nobility Jaime de Oriel Lopez Montenegro and his wife, Leyla (herself, a princess from the Ottoman Empire); and Kitty Lai, known as the Queen of Jeans in London.