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 Henry Grant B ???? somewhere in Ireland with a father forenamed Peter, I found ONLY 1 rcd in 1829, Co. Down. This doesn't fit either your timeline or location.
For Henry Grant M ???? B4 1880 in Armagh, Down and Louth, I found 5 rcds: 2-1874 Armagh, 1874 Down, and 2-1979 Down.
For Ellen Rice M ditto, I found 7 rcds: 3-1872 Armagh, 1872 Down, 2-1873 Kilkenny, and 1880 Down. There are NO potential matches to Henry's rcds. Either the event wasn't rcd'd, or they married in America. The latter seems more likely as rcd keeping was good by this time.
For Betty Woods M ???? somewhere in Ireland, I found 4 rcds: 1775 Louth, 1818 Louth, 1843 Cavan and 1846 Louth.
For Peter Grant M ditto, I found no matching rcds to those for Betty.
For Alice O'Hare M 1842-1859 in somewhere in Ireland, I found 1 rcds: 1843 Down, 2-1848 Armagh, 1850 Down, and 1858 Louth.
For John Rice M ditto, I found 31 rcds. One in 1843 Down potentially matched those for Alice. Searching at the parish level, I found a match in Newry & Mourne RC parish.
The above Rice M rcds are highly likely to be for your ancestors - no guarantee. A view of the detailed rcds will show whether the M was to each other. If so, the rcds SHOULD also show their parent's names.
For Ellen Rice B 1847 +/- 4 yrs in Co. Down, I found 7 rcds. One in 1848 was in Newry RC parish. A view of the detailed rcd SHOULD show the correct parents, thus validating/invalidating the rcd.
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.