Question: Who is Princess Antoinette, Baroness Of Massy's sibling-in-law?
Sentence (from "Princess Antoinette, 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.
Relevant evidence: Yes