See fourth record 1870 civil marriage record. Names of fathers listed https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_ret...
Is this your O'Connell family in the 1901 census? http://www.census.nationalarchives.ie/pages/1901/Kerry/Portmagee/Portmag... John is not included. Civil parish is Killemlagh and RC parish was Prior/Ballinskelligs
see fourth record likely death record for John O'Connell 1926 https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_retur...
did not locate Mary's death record.
Have you considered DNA testing?