HRH Charles's 16-Great Half-Aunt. Philippe of Belgium's 17-Great Half-Aunt. Grand Duke Henri's 17-Great Half-Aunt. HM Margrethe II's 16-Great Half-Aunt. HM Constantine II's 16-Great Half-Aunt. HM Carl XVI Gustaf's 16-Great Half-Aunt. HRH Catharina-Amalia's 18-Great Grandmother.