William Alexander Duncan, b. 1 Nov 1837 in Oswego County, Oswego County, New York, d. 31 Oct 1916 in Middleton, Orange County, New York, son of William Duncan & Mary Wood. He married Julia B. Coleman in 1868.
William Butler Duncan, Jr., b. 1 May 1862 Providence, Providence County, Rhode Island, d. 30 Mar 1933 in Manhattan, New York County, New York, son of David Duncan & Fannie Bloodgood. He married Blanche "Blanca" Maximillan Havemeyer on October 15, 1891 in Newport, Newport County, Rhode Island. (He was adopted by his paternal uncle William Butler Duncan after his parent’s early deaths)
William E. Duncan, b. Jun 1859 in Milwaukee, Milwaukee County, Wisconsin, d. 28 Apr 1911 in Green Bay, Brown County, Wisconsin, son of John Duncan & Margaret McEwen. He married Heloise M. Duchateau on June 27, 1883 in Green Bay, Brown County, Wisconsin.