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The RC baptismal records for Kiltimagh parish start in February 1861. Likely there were addiitonal children besides John born between 1852 and 1861. On the free site www.irishgenealogy.ie I located the civil birth record for Michael Murtagh and an 1866 civil birth record for Thomas Murtagh.
Here is the 1901 census record for Thomas Murtagh born 1866 with his wife, child and his sister Mary.
Bridget Murtagh died in 1895 and Patrick Murtagh in 1897. The informant was John Snee son in law on both documents.