I just found your site. I have had William Day and Nelly Corder but have not seen her as Nancy.
Their marriage is listed in the "Virginia Marriages- 1740 to 1850". She is there as Nelly.
Virginia, Marriages, 1740-1850
about Nelly Corder
Name:Nelly Corder
Gender:Female
Spouse Name:William Day
Spouse Gender:Male
Marriage Date:26 Sep 1785
County:Fauquier
State:Virginia
I know little else about her other than that her father was James 1740-1803 ,Farquier, Virginia, USA, whose wife was probably Elizabeth.
If you have more about the Nancy name I would be interested.