Complex sentence: A daughter, Henrietta Joan Tiarks, who married Robin Russsell, The Marquess of Tavistock, who eventually became The 14th Duke of Bedford and a son, Edward Henry Tiarks who died when he was only six months old in 1943.
Split into simpler sentences: A daughter, Henrietta Joan Tiarks, married Robin Russsell, The Marquess of Tavistock, who eventually became The 14th Duke of Bedford. A son, Edward Henry Tiarks, died when he was only six months old in 1943.