The Donald Mackay mentioned in your posting was a Donald Mackay (d.1768), thought to have been a member of the family of an early Lord Reay, Chief of Mackay, who settled on the northern end of St. Simons Island, GA. He is known to have had a daughter, Mary Catherine Mackay. Catherine/Katherine, as she was more commonly known, married William M"Intosh (Mackintosh, son of the famous John Mor M'Intosh and his wife, Marjory Fraser, who settled at Darien, GA. William was boen in 1726, Scotland, and came to America with his family in 1736.Catherine and William had Marjory b.3/26/1774; d.1818), who married James Spalding, late of Ashantilly, Perthshire, Scot., who came to Georgia in 1760. Their son was the well known Thomas Spalding "Laird of Sapelo" Island. Thomas married, on 11/5/1795, Sarah Leake, and had about 14 children of the surname Spalding.