For some strange reason I am only today coming across your reply to my query! I wonder if there was a glitch with GenForum the day you posted. . .
I suppose it would depend upon how many Thomas Lyons lived at Old Park around 1800 to have any certainty that your ancestor might have been the uncle of John Lyons in America. But it does seem plausible that we could be talking about the same man.
I am certainly interested in exchanging any further information on your Lyons with the thought that there could be a relationship to my known Greers!
I could do some checking on this side to see if your Thomas' brother, William, was in America (if you are interested). It would seem to indicate that if John Lyons left everything to his uncle, Thomas, that there were no others in his family in America to left his 'estate' to.
Thank you for responding to my query and I apologize for being so late in anwering you!