Question: Dorothea von Salviati's father-in-law was born on what date?
Sentence (from "Princess Dorothea of Courland"): Her mother was Dorothea von Medem, Duchess of Courland, and although her mother's husband, Duke Peter von Biron, acknowledged her as his own, her true father might be Polish statesman Aleksander Batowski.
Relevant evidence: No