Question: Who is the mother-in-law of Lady Brigid Guinness?
Sentence (from "Lady Brigid Guinness"): Lady Brigid Katharine Rachel Guinness (30 July 19208 March 1995) was the youngest daughter of Rupert Guinness, 2nd Earl of Iveagh, and wife of Prince Frederick of Prussia, grandson of Wilhelm II, German Emperor.
Relevant evidence: Yes