Complex sentence: Lady Frances Manners (24 March 1753--15 October 1792), Countess of Tyrconnel, was the daughter of John Manners, Marquess of Granby and his wife Lady Frances Seymour.
Split into simpler sentences: Lady Frances Manners (24 March 1753--15 October 1792), Countess of Tyrconnel. She was the daughter of John Manners, Marquess of Granby and his wife Lady Frances Seymour.