Jack, missed your response somehow.
I was always under the impression that William and John went to SC just after the Revolutionary War.William stayed in Horry until about 1815 then moved to Brittons Neck for the remainder of his life. This may not be the same William and John that Sellers was refering to but I took them to be one and the same. Since William was 14 in 1777 and in NC then he probably wouldn't have had any knowledge of the Roanoke, VA in the mountains. I just don't see him getting VA newpapers in Brittons Neck to know of the name change and Brittons Neck does not seem to be a major thoroughfare for travelers that would pass on information. Assumptions are always a killer to new leads but I just can't see him saying he was from Roanoke and meaning the one in the mountains if it was called Big Lick or anything else when he lived there, but then stranger things have happened.