There was a Brown family in Essex Co., VA that has been accurately traced back to a Francis Brown "I" (who died there in 1691). There was also an adult Thomas Brown in Essex in the late-1600s who APPEARS to have been a younger brother, nephew or cousin of Francis Brown "I." A later Thomas Brown (born early-1740s), who was APPARENTLY a member of this same overall Brown family out of Essex Co., VA (based on a few clues), lived in Lunenburg (later Mecklenburg) Co., VA. His Mecklenburg Co., VA will (written 8 Dec 1783; recorded 6 June 1794; proved 9 June 1794)was witnessed by a man named Cluverious Coleman, and that same overall Coleman family had been closely associated with the Browns back in Essex Co., VA. The Thomas Brown in Lunenburg/Mecklenburg married a Mary Pettus, and I see that there was a also a "Pettus connection" with your Coleman family out of Amelia Co., VA.
A Henry Brown from the family of the above-mentioned Francis Brown "I" moved from Essex Co.,, VA to Lunenburg (later Mecklenburg) in the early-mid-1760s. As such, I would not be surprised if the Nancy Brown who married into your Coleman family was either from the family of the above-mentioned Thomas Brown or from the family of this Henry Brown. As a matter of fact, the above-mentioned will of Thomas Brown showed that he had a daughter named Nancy Brown (so the name "Nancy" was obviously used in that branch of the family). In addition to Nancy Brown, Thomas Brown also had children named Pettus, Thomas, James, John, Mary (married to a Walker), Rebecca (married to a Wilson), Olive and Martha Brown. Other women mentioned in the will who MIGHT have been married daughters of Thomas and Mary (Pettus) Brown were Elizabeth Neal and Amy Hutcheson.
There was also an "unknown" Francis Brown (born about 1700) in Essex Co., VA whose parents have not been proven (but his father COULD have been the "oldest/first" Thomas Brown mentioned above who was an adult in the late-1600s in Essex). This "unknown" Francis Brown was married to a Christiana Unknown, and one of their sons named Hezekiah Brown moved from Essex Co., VA to Amelia Co., VA in the mid-1700s. It appears that a son or grandson of this Hezekiah Brown, who was also named Hezekiah, married a Tabitha Irby in "next-door" Dinwiddie Co., VA in the 1780s. DNA from a living male Brown descendant of this last Hezekiah Brown proves that this was, in fact, yet another branch of the same overall Brown family as Francis Brown "I." The older Hezekiah Brown mentioned above had a brother named Thomas Brown (among several other siblings), so that is another clue that the "unknown" Francis Brown MIGHT have been a son of the "first/oldest" Thomas Brown in Essex Co., VA. I don't know if this "Amelia/Dinwiddie" branch of the "Essex Co., VA Brown family" had any "interaction" with your Coleman family while both families were in Amelia Co., VA.