Technically, the Grimaldis of today are cousins (albeit distant cousins) of the Duke of Hamilton. Related through Lady Mary Victoria Douglas-Hamilton, the mother of Prince Louis II of Monaco and wife of Albert the First, Lady Mary was the daughter of the 11th Duke of Hamilton.
Albert was her first husband. She had a daughter with her second husband, Tassilo Festetics de Tolna, Prince of Hungary. The daughter was Alexandra, Countess of Tolna. So Louis II had a sister.... does anyone know about the sister's line? Alexandra married into the Windisch-Gratz family. Alexandra's daughter then married into the Collalto family, also a German princely family.
How is Prince Albert (the Second) related to the present Duke of Hamilton? How is he related to the current Prince von Collalto und San Salvatore?
How is he related to the current Prince zu Windisch-Gratz?