Premise: Princess Antoinette of Monaco, Baroness of Massy (Antoinette Louise Alberte Suzanne Grimaldi; 28 December 1920 – 18 March 2011) was a member of the princely family of Monaco and the elder sister of Prince Rainier III and aunt of Albert II, Prince of Monaco. Her parents were Count Pierre de Polignac and Princess Charlotte, Duchess of Valentinois.
Hypothesis: Princess Antoinette of Monaco siblings were Count Pierre de Polignac and Princess Charlotte, Duchess of Valentinois.