There are Adair researchers who have documentation on this James Adair, but am listing some references and connections -
James Adair is mentioned as being a neighbour of Randal McDaniel. The land McDaniel purchased 1780 from Robert Robinson was on the waters of the JAMES river, called Broad Creek, Rockbridge Co. VA. James Adair's land also apparently joined that of Thomas Leech and Robert Montgomery. In 1809 McDaniel sold this land to Martha Miliken.
On April 1 1783 William & Martha Miliken sold land to Samuel ADAER for fifty pounds, 44 acres. Rec. April 6 1784 (names are spoken "Milliken" and "Adair"). Rockbridge Co., VA Deed Book A, p. 427 (Deed Abstracts, p.45).
In the Old Monmouth Presbyterian Church (c.1741) Cemetery which was located then on the north branch of the JAMES River (named changed from James River to Maury River),
there are the graves of John Adair, Jan 5 1817 - April 13 1885 and Samuel Adair c.1809 - July 11 1895.
The Church is evidently now called the New Monmouth Presbyterian Church located on Rt.60 near junction of 631.
In the Rockbridge Co. VA, Marriage Bond Index 1778-1801 there is the record of marriage between Martha Adair and Daniel LYLE (the Lyle family were from Browndodd, Larne, Ireland). Bondsman was Samuel Houston and witnesses were George Adair and Samuel Houston. Parent of Martha Adair was Benjamin Adair. (Believe I have in my files a marriage of a Samuel Houston with an Adair, in Ireland).
Another Adair who was mentioned as being in Rockbridge County was the daughter of William Adair (Wm. dc1763).
Sarah Adair m. Roger Keys and after he died she married Samuel McSpadden and they had a son Samuel b. Oct 10 1756 near Lexington, Rockbridge Co. VA.
Samuel McSpadden came to America possibly with the LYLE family from Ireland, they were originally of Scottish descent and he purchased land in the Borden tract in what is now Rockbridge Co. VA.
There was an Elizabeth Lyle who m. Samuel Ramsey and a dau, Margaret m. George ADAIR, and a son Samuel Ramsey m. Mary Keyes. (Sorry if you are by now completely confused).
There was a John Adair of Rockbridge Co. VA in the Virginia Land Deed records who witnessed a deed in Deed book #26 on Aug 1 1787, other names were John, Robert & Elizabeth Bell, James Rowland, David Wilson and John Fulton.
Then there was the estate of John Addair, Jr. 1848 Rockbridge Co. VA, Deed book K (1815-1817) p.4.,
may have been on "Beverley Manor".
There are excellent original records of the marriages bonds, etc. at
http://www.rootsweb.com/~usgenweb/va/rockbridge/images/1787/...etc. I will try and translate them.