Thanks, Frances, and also for the Jurby John Corkill marriage details (both of this parish). The compiler of the IGI family tree had no sources giving an age for him, nor any explanation as to why she chose a Maughold John Corkill to marry Ann Teare. The husband could have been any one of numerous John Corkills bapt in the mid 1700s (married in 1796, bur. 1805 - both Jurby).
A quick look at Familysearch shows about 38 bapts of John Corkills in the mid 1700s, from Ballaugh, Lezayre, Andreas (many), Maughold, & Braddan, as well as parishes further away - all except Jurby - and the family tree compiler could have chosen any of them.
I don't think the Ards eldest son was a good choice to be the one living in Jurby, because (1) if staying in the IOM why would he leave land held by the family for several generations, and (2) his gt niece said he had gone to America.
Sue