Complex sentence: Gertrude Vanderbilt Whitney (1875-1942) was a daughter of Cornelius Vanderbilt II and married Harry Payne Whitney, wealthy son of a prominent New York attorney.
Split into simpler sentences: Gertrude Vanderbilt Whitney (1875-1942) was a member of the prominent United States Vanderbilt family. Gertrude was a daughter of Cornelius Vanderbilt II, She married Harry Payne Whitney, the wealthy son of a prominent New York attorney.