Complex sentence: His first wife was Mart daughter and cohier of James Macartney of Longford nephew and coheir of Ambrose Aungier, 2nd Earl of Longford by whom he had three children including George Fulke, his successor.
Split into simpler sentences: His first wife was Martha, daughter and coheir of James Macartney of Longford, nephew and coheir of Ambrose Aungier, 2nd Earl of Longford. They had three children including George Fulke, his successor.