Complex sentence: She encouraged her son Charles Emmanuel to marry her niece Françoise Madeleine d'Orléans, the youngest surviving daughter of Gaston, Duke of Orléans, her youngest brother.
Split into simpler sentences: She encouraged her son Charles Emmanuel to marry her niece Françoise Madeleine d'Orléans. She was the youngest surviving daughter of Gaston, Duke of Orléans, her youngest brother.