It is very possible that William had a daughter named Susan. The Nunn side is my direct line and according to the book "The Nunns of the 18th Century Va" by o. Norris Smith it said that William Alexander was niece to Betty/Susan Alexander.William Alexanderfirst claimed of land was on the Smith River in 1752.and that is listed in Book of Surveys Pittsylvania Co., #1 p. 5. Betty/Susan Alexander was married to Thomas Nunn by 1765 probably in Henry Co. VA.
I also have a Lucy Nunn b c. 1750 -d 1815KY married 1769 John Alexander.
I am interested in the Alexander Family because the Nunn family and Alexander Family seem to have married each other serveral different times in history. Thank-you for your help Michael