All I have is some circumstantial information but it may help.
I have been studying the family of John Butler d. 1757 and his descendants in Culpeper County. John who died 1757 had sons James, Thomas and John Jr. John Jr., married to Mary Taylor had known sons William b. 1754 and Aaron, b. c. 1775. Suspected other sons without a smoking gun as yet are John b. 1762, Benjamin b. 1765 and Elijah, b. about 1778, who married Catharine Watts, daughter of Frederick Watts.
John Butler Jr. held land for most of his life on Sumerduck Run. Also in the Sumerduck Run area are lands held by Frederick Watts since 1741. Frederick Watts was also named in the will of Frederick Kabler, his grandfather !
Thus there is an associate between Butler, Watts and Kabler where they are linked by location and by association in wills and court records. James may even be another son of John Jr--or James or Thomas.
One sure way of telling where your James might belong is if he has a Butler descendant that can do the DNA test. This is the only way I have been able to sort out all the John Butlers klying around VA at the time.