Question: Who is Frederick Iv, Duke Of Holstein-Gottorp's maternal grandmother?
Sentence (from "Frederick IV, Duke of Holstein-Gottorp"): According to Robert Massie's "Peter the Great: His Life and World", Duke Frederick arrived in Stockholm to marry his cousin, Princess Hedwig Sophia, soon befriending his first cousin and new brother-in-law, King Charles XII (their respective mothers, Frederica Amalia and Ulrika Eleonora, being daughters of Frederick III of Denmark).
Relevant evidence: No