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 county, 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 Stephen Gavin B ???? somewhere in Ireland with a father forenamed Pat(rick), I found 0 rcds. He may have been born in America.
For Pat(rick) Gavin M 1867 +/- 4 yrs, I found 7 rcds: 1863 St. Nicholas, 1864 Moycullen, 1865 Kilcummin-Oughterard, 1866 Moycullen, 1867 Milltown, 1867 Moycullen, and 1870 Kilcummin-Oughterard.
For B(ridget) Flannagan M ditto, I found 6 rcds: 1863 Clonbur, 1864 Tuam, 1865 Ballyconneely, 1865 Annaghdown, 1866 Ardrahan, and 1867 Castlegar. There are NO matching rcds with those for Pat(rick). Three explanations: 1) the search range is wrong. 2) They married outside Galway west. 3) The rcds didn't survive.
For Pat(rick) Gavin B 1845 +/- 4 yrs, Kilcummin-Oughterard, Co. Galway, with the father's forename unknown, I found 1 rcd in 1845. The father's forename was Stephen.
For Bri(dget) Flannagan B 1847 ditto, I found 8 rcds: 1844, 1845, 2-1846, 2-1848, 1850 and 1851. However, NONE of these is in Kilcummin-Oughterard.
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.