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I searched on the subscription site Roots Ireland for any Reilly baptismal records in Ireland where the mother's surname was Berrigan or Bergin but did not find any records.
I am helping a friend whose family originated in Kilkenny, she thinks Cavan. Unfortunately we don't have too many dates. Her father was James O'Reilly or Reilly b. Kilkenny 1921, her mother was Mary d.2006. The person we are trying to find is also James O'Reilly, James' father. Her grandmother, James's mother was Ellen Berrigan born around 1880 and died at the age of 90. I have been told that this name might be spelt wrongly because of Irish pronunciation and may be something like Bergan. She and James had 5 children, James as mentioned, Thomas, Patrick, Maureen and Helen. James the senior left Ireland for Boston in US sometime after the war and died there in an accident.
I have searched all the usual places Irish Ancestry, Familysearch, Irish Genealogy but with no luck. There are so many people with the same names I can't match the name to any of the dates with have. Maybe somone in Kilkenny can throw some light on the family for us.