I research the Irish Family History Foundation's database. It contains 12,700,000 surviving rcds for abt 70% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 30%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For James Keating B 1842 +/- 4 yrs, Co. Dublin, with a father forenamed John, I found 2 rcds, 1842 Swords RC parish and 1844 ????.
For John Keating M 1838 ditto, somewhere in Ireland, I found 40 rcds - too many to easily summarize here.
For Mary Mulholland M ditto, I found 28 rcds. Will leave it to you to match these up with those for John.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.