Complex sentence: Ailsa Mellon Bruce (1901-August 25,1969), born in Pittsburgh, the daughter of the banker and diplomat Andrew W. Mellon (1921-1932) served as her father's official hostess during his tenure as US Secretary of the Treasury.
Split into simpler sentences: Ailsa Mellon Bruce (1901-August 25,1969), born in Pittsburgh, the daughter of the banker and diplomat Andrew W. Mellon. Mellon-Bruce served from 1921 to 1932 as her father's official hostess during his tenure as United States Secretary of the Treasury.