Complex sentence: He married Maud Thompson, who was the sister of the well-known Shakespearean actress Constance Crawley, and his sister Amy Dora Percy was a novelist under the pen name of Mrs. Fred Reynolds.
Split into simpler sentences: He married Maud Thompson, who was the sister of the well-known Shakespearean actress Constance Crawley. His sister Amy Dora Percy became a novelist under the pen name of Mrs. Fred Reynolds.