After looking at James McFarland's 1805 will more closely, it appears that the witnesses were: James Alexander, Betsey Alexander, and Nancy Alexander. Patricia Roberts has: James Alexander b. 1764 md. Elizabeth Ross b. 1769, with two daughters: 1. Esther Sharp Alexander b. 21 Feb 1789 [md. Morrison] 2. Nancy Ross Alexander b. 1791
It appears that the witnesses of James McFarland's will probably were James Alexander and his wife Betsey and their daughter Nancy. If you determine anything about these Alexanders, please let me know. They may be related to my McFarlands and may be a clue to the maiden name of James's wife Rebecca.
I notice that you have different dates for these Alexanders. Do you have a bbirthdate for Nancy Ross Alexander?