Complex sentence: Hortense Félicité de Mailly married François-Marie de Fouilleuse, marquis de Flavacourt, in 1739, and was appointed "dame du palais" to queen Marie Leszczynska in 1742, the same year her sister Marie Anne de Mailly became the official mistress of the king.
Split into simpler sentences: Hortense Félicité de Mailly married François-Marie de Fouilleuse, marquis de Flavacourt, in 1739. She was appointed "dame du palais" to queen Marie Leszczynska in 1742, the same year her sister Marie Anne de Mailly became the official mistress of the king.