Complex sentence: They had no children, but they fostered the four children of his brother George whose wife Kezia (née Parker), had died in childbirth, he adopted a son, Ernest, and also brought up three other children.
Split into simpler sentences: They had no children but fostered the four children of his brother George, whose wife, Kezia (née Parker), had died in childbirth. He adopted a son, Ernest, and brought up three other children.