Deposed by the Russians in 1736, Stanislas had the good fortune to be Louis XV's father-in-law and was given the Duchy of Lorraine as compensation.
The Duchy of Lorraine was never given to Stanislas by Louis XV. 
mnli hypothesis: The Duchy of Lorraine was never given to Stanislas by Louis XV.  premise: Deposed by the Russians in 1736, Stanislas had the good fortune to be Louis XV's father-in-law and was given the Duchy of Lorraine as compensation.