I'm really enjoying reading your posts and learning more about the way society operated in Eastern NC. I read in Paul Heinegg's book that slaves were not permitted to legally marry, but were allowed to cohabitate. Based on upon this premise, I believed that if I found marriage licenses for my family members prior to emancipation, and they were listed in the Federal census, these were indeed free people of color.
I know in theory that the census is only supposed to count a person at their place of residence. However, as I reviewed census records for Beaufort County in 1850 for every person surnamed Keys, I found that apprenticed and/or bonded children were often counted at their family residences and at the residences where they worked. I also notice that both the parents may be called Mulatto, but the children may be called Black; I have come to disregard this information to a degree, because it was probably a function of appearance (complexion, hair color/texture, facial features) and perception (my 2GGpa was categorized differently many times over his 100+ year lifespan) versus strict application of the 3/4, 1/2, 1/4, 1/8 rules used in other slave states. My 2GGpa was very fair in complexion with straight hair, according to his family and my grandmother who married into the family.
I will keep plugging away online, but I may not be able to get to the court documents you recommend until I visit NC next spring or summer. I am working on determining whether Washington Keys was my 2GGpa's brother and trying to definitively rule out the Mulatto Rhoda Pierce.