I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN parish, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
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 Bri(dget) O'Hare (+variants) B 1864 (exact) in Dundalk (Co. Louth), I found 1 B rcd. Her father's forename was John. The parish was Carlingford.
For Cath(erine) " B ???? in Carlingford with a father's name of John, I found 1 B rcd in 1858.
For Pat(rick) " B ???? ditto, I found 1 B rcd in 1875.
For Peter " B ???? ditto, I found 1 B rcd in 1880.
For Michael " B ???? ditto, I found NO rcds.
The above are likely to be for your ancestors. Caution - there are at least two other families headed by a John O'Hara in this parish. You will have to check the wife's name to separate your ancestors from the others.
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.