Complex sentence: From her staff at Versailles, Marie Anne introduced her older half brother the Dauphin, to his second morganantic wife, Émilie de Choin, whom he married after the death of his first wife, the unattractive Dauphine Victoire (1660-1690).
Split into simpler sentences: From her staff at Versailles, Marie Anne introduced her older half brother, the Dauphin, to his second wife, Émilie de Choin. He married her morganatically after the death of his first wife, the unattractive Dauphine Victoire (1660-1690).