Al.... my Davidson family has a similar situation.We currently have three male DNA donors whose DNA matches our DNA, but whose surname is "Bishop" instead of "Davidson."We are currently looking for the "most recent common male ancestor" in that "male DNA line."
My Davidson family (which includes the Charles Davidson mentioned in this message board "thread"....though Charles is/was not a member of my "direct line") was in James City Co., VA (JCCo) by at least 1682.A member of that Davidson family named Ezekiel Davidson died in "next-door" Charles City Co., VA (CCCo) in 1762, and Ezekiel took his relative Stephen Davidson to chancery court in 1762 (just before Ezekiel died).Four other "non-Davidson" men (and their wives) joined Ezekiel Davidson in that suit against Stephen Davidson. I suspect that the four wives were all married Davidson women.One of the four "non-Davidson men" who joined Ezekiel Davidson in that court case against Stephen Davidson was a William Adams (who was married to a Lucy....probably Lucy Davidson).
I have no idea if the above Adams family in CCCo was related to "your" Robert Adams of Goochland Co., VA....but I thought that I should make you aware of the referenced chancery court case.Some of the other Davidsons in that same overall family in JCCo/CCCo (Edward, David and William Davidson) were in Goochland Co., VA by the 1740s.By the way, it appears that all of the above Davidsons were sons (or some might have been grandsons) of the David Davidson, Junior who was born by at least 1688 in James City Co., VA, and who died about 1756 in CCCo (and the above Stephen Davidson was the executor of David Davidson, Junior's Will in 1756).If the Adams family in CCCo in 1762 had also been in that same area in the late-1600s (like the Davidsons were), then maybe "your" Robert Adams in Goochland could have come from JCCo/CCCo.