The Rev. Waitstill Sharp and his wife, Martha, were a young Wellesley couple busy raising two young children in 1939 when they received a call from the American Unitarian Association asking for help. Nazi Germany was gaining control of parts of Czechoslovakia, and the Boston-based denomination was looking for a couple to lead a humanitarian effort to rescue political dissidents and Jewish refugees from Prague. Sharp was the minister at what is now the Unitarian Universalist Society of Wellesley Hills. He and his wife were interested in foreign affairs, and they were the first couple to say “yes’’ to leaving their children and risking their lives after 17 other couples said “no.’’