Thanks for your post. My ancestor Elijah Adams (born probably around 1760) married Hannah Blair, daughter of William and Hester Blair and a native of Ireland, in Bedford County, PA, probably around 1782-3. Their daughter Hester (1785-1846) married William McKee and was my ancestor. Hester was a Methodist, and, according to her obituary in the Western Christian Observer (a Methodist newspaper), she was the daughter of Elijah and Hannah Adams. Her son John Adams McKee was a licensed Methodist preacher in Illinois.
Elijah was in Pennsylvania through 1792, but before 1797 he moved to Kentucky, and from 1797 to 1800 he was in Montgomery County. I suspect, because Hannah Blair's brother(s) lived there, that Elijah lived in Westmoreland Co., PA prior to KY.
Because of the Bedford and Westmoreland County and Methodist connections, I strongly suspect now that Elijah was the brother of your ancestor Robert.
I have wavered between deciding whether the Elijah who went to Kentucky was the son of Elijah Adams (d. 1798/9, Bedford Co.), or whether the Elijah Adams who died in 1863 and was a merchant in Bedford was the son. But the Kentucky Elijah had a son Ephraim, as did the elder Elijah, so there is another link.
What is the source for the birth year of Robert Adams (1753)? Is it a guess, or is it from a gravestone or other source? This would be important in establishing the older Elijah's approximate year of birth. Hannah (Blair) Adams's brother, Alexander Blair, lived at Mount Pleasant, Westmoreland Co., PA, in the 1790s, prior to moving to Kentucky. Did Robert Adams live anywhere near there? In 1800, the census index shows a Robert Adams and a James Adams on the same census page. Was this James Adams, who married Hannah, daughter of Elijah and Hannah Adams?
I'm also interested in the Blairs. William and Hester had various children, but no Keziah. However, William seems to have had a brother Alexander (in Cumberland Co.) and possibly was related to Brice Blair, of Bedford Co.