Complex sentence: However family historian, Kathleen Whiteing Fitzgerald, revealed that Richard had two brothers, Robert & George, who lived well into adulthood and a sister Elizabeth who died as an infant.
Split into simpler sentences: However family historian, Kathleen Whiteing Fitzgerald, revealed that Richard actually had three siblings. There were two brothers, Robert & George, who had both lived well into adulthood and a sister Elizabeth who died as an infant.