I research the Irish Family History Foundation's database. It contains 12,800,000 surviving rcds for abt 70% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Cos. Donegal and Derry were recently added to the database.
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 available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome), and the National Library of Ireland on microfilm.
For Hannah Toomey (+variants) B 1886 +/- 4 yrs, Co. Cork, with a father forenamed Cornelius, I found 1 rcd, 1886, Glantane RC parish. A view of the detailed rcd SHOULD show her parent's names.
For POSSIBLE siblings B Glantane RC parish with a father forenamed Cornelius, I found only a Mary B 1882, nothing for the others. They may have been born elsewhere.
For Cornelius Toomey M 1882 +/- 4 yrs, Co. Cork, I found 2 rcds: 1880 Castlemagner and 1885 Lisgoold RC parishes. One of these MAY reveal the bride and groom names found above. It may also show their parents' names.
For Cornelius Toomey B 1845 +/- 4 yrs, Co. Cork, with the father's forename unknown, I found 10 rcds: 1841 Macroom, 1842 Lisgoold, 1843 Donoughmore, 1844 Coachford, 1844 Killnamartyra, 1845 Killnamartyra, 1846 Macroom, 1847 Ballyvourney, 1848 Newmarket, and 1848 Donoughmore RC parishes.
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.