I was going to suggest that you try appealing for help, just as you did Ian. Hope Allen's leads pan out. What I do too, is look for more general information elsewhere, such as looking up origins of the last name. My curiosity bore fruit when I gathered much information about the clan, where the name was most common, and I even found where the Ancestral seat of the clan was. It still bears the name Ballymacarney and is just outside Dublin city limits. And when I found out where the emmigrants to Canada had come from, I was "gob-smacked" The Carneys came over from Clondalkin, not far from Ballymacarney at call. The Cavanaghs had come from Carlow, just 50 miles south of Dublin. Both families gravitated to Goderich Ontario, which is very near to some towns with Irish names, like "Carlow, Killarney, Lucan " and others. Seems that people went where there might be some familiar names or even faces from home. Many rejoined relatives in the new land. Study some history too. There was always " context" for immigration, esp. in Ireland, Scotland, etc.
