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 ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Bri(dget) McGuiness B 1824 +/- 4 yrs, Co. Louth, with the father's forename unknown, I found 9 rcds: 1820 Dundalk, 1820 Dunleer, 1820 Dundalk, 1821 Collon, 1821 Dundalk, 1821 Drogheda, 1822 Tallanstown, 1826 Dundalk, and 1827 Haggardstown. None were in Carlingford RC parish. Father's respective forenames were James, Tho(mas), ????, John, Bryan, Pat(rick), ????, John, and "Jno."
For Peter McGuiness B ditto, I found 6 rcds: 1821 Haggardstown, 1821 Haggardstown, 1824 Darver, 1825 Dundalk, 1826 Dundalk, and 1827 Dundalk. Father's forenames were Tom, Tom, John, James, James, and Bryan.
For Mary McGuiness B ditto, I found 23 rcds - too many to easily summarize here.
For Mic(hael) McGuiness B ditto, I found 5 rcds: 1824 Drogheda, 1826 Haggardstown, 1826 Haggardstown, 1827 Dundalk, and 1828 Dundalk. Father's respective forenames were Mich(ael), Pat(rick), Mich(ael), John, and Owen.
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.
Hope this helps. Good luck.