Complex sentence: When Dorothy gave birth to a son, Omar Pound, in France in 1926, Olivia assumed guardianship of the boy, who lived with her until her death on 3 October 1938.
Split into simpler sentences: When Dorothy gave birth to a son, Omar Pound, in France in 1926, Olivia assumed guardianship of the boy. He lived with Olivia until her death on 3 October 1938.