Perhaps the reason Nancy Tapscott was mentioned, was that she was considered a member of the family.
I have seen varying descriptions of this Nancy as being born blind, and being 65 years of age. I really need to see the Census records to be sure of what they really intended.
A record of a Nancy Tapscott exists in the 1850 Census for Caswell County with several others who seem to be her siblings, given the age range. That census does list her as age 54 and blind. I wonder if this were the same Nancy that you have seen. The abstract of the Census did not list the race for the Tapscotts given. (Another thing to check)
Winston Salem, NC