Thanks for all this. Must take some time to look at it in more detail.
I'm not sure which Richard Shevlin this would be, perhaps John Shevlane's brother? My Anne Barrett was born c.1820, so her marriage isn't recorded to Michael Shevlane, too long ago.
I notice Shevlane is a pretty uncommon surname, even in Ireland. I wonder if there are any other fragments of information about the family origins? It seems much less common than Barrett, or the like.