Complex sentence: He married twice: his first wife was Elizabeth Barnewall.and had one son, Thomas, and a daughter, Ismay, who married James Fleming and was mother of Thomas Fleming, 10th Baron Slane.
Split into simpler sentences: He married twice: his first wife was Elizabeth Barnewall. He had one son, Thomas, and a daughter, Ismay, who married James Fleming and was mother of Thomas Fleming, 10th Baron Slane.