A family of Syrian refugees had been invited to dinner in a penthouse atop the Waldorf Towers, the official residence of the United States ambassador to the United Nations. [...] Morad and Ola Al Teibawi, and their five children — ages 3 to 17 — came to the Waldorf from their tiny apartment in Paterson, N.J., on Monday evening, guests of Samantha Power, the United States ambassador to the United Nations, and her husband, the writer and law professor Cass Sunstein.