HRH Charles's 16-Great Aunt. Philippe of Belgium's 17-Great Aunt. Grand Duke Henri's 17-Great Aunt. HM Margrethe II's 17-Great Grandmother. HM Beatrix's 16-Great Grandmother. HM Constantine II's 17-Great Grandmother. Wm. von Bismarck's 11-Great Aunt. `Red Baron' Richthofen's 14-Great Grandmother.