I assume your ancestors were Church of Ireland? I searched for a marriage record for this couple with no success. Starting in 1845, non-Roman Catholic marriages were supposed to be civilly registered yet I did not see a reocrd on the free site www.irishgenealogy.ie
I also did not find any baptismal records for the children. civil registration of births began in 1864.
Likely the events took place in a parish where records are not available. Many of the Church of Ireland pre-1870 records were lost in the Public Records Office fire in 1922. There is also the possibility that the records are held locally or at the Representative Church Library in Dublin. However, until we determine the parish, we can't know for sure whether records are still available.
You may want to consider DNA testing. You may get matches with third cousins who have more info on the origins of the family in Ireland.