Lisa, thanks for the info. The Archibald McRobert you mention in your posting was actually the grandson of the Rev. Archibald that I'm researching. The Archibald McRobert who married Maria Blackbourne was born in 1777 and died 1824 in Alabama. He was the son of Theodorick Bland McRobert (who was the son of the Reverend) and Agnes Woodson Morton.
Am still interested in any information anyone out there may have on Rev. Archibald McRobert of Prince Edward County, and especially any connections to the Watt family of Buckingham County, Virginia. Alexander McRobert, a merchant in Richmond and also Archibald's brother, died in 1798 in Richmond. He apparently died childless and left his estate to his wife Mary, his brother Archibald, and "the children of William Watt of Buckingham County." Early records from Buckingham Co. were lost. Am trying to discover the relationship between Alexander McRobert and William Watt (perhaps William Watt married the sister of the McRobert brothers?).