My Grandfather Thomas McKeown Married Ellen Callan circa 1920. They travelled to Scotland where they lived for the rest of their lives. Some of the family left behind may have gone to various places like the US but some may have stayed in Ireland.
Thomas:
Based on this civil marriage index record, it appears Thomas and Ellen were married in the fall of 1913. I also found Thomas with his family in the 1911 census. http://www.census.nationalarchives.ie/pages/1911/Monaghan/Kilmurry/Cargaghlisnanarney/798791/
If you want to get a copy of the marriage record from the GRO, let me know and I'll send you the instructions. A copy costs around 4 euros.
Roger McDonnell
Name: Thomas