Complex sentence: A member of the Jockey Club, Weinstock owned a number of thoroughbred racehorse including co-ownership with his father-in-law in Troy, winner of the 1979 Epsom Derby.
Split into simpler sentences: A member of the Jockey Club, Weinstock owned a number of thoroughbred racehorse. He and his father-in-law owned Troy, winner of the 1979 Epsom Derby.