I searched the ROOTSIRELAND.IE database. It contains 19M B/M/D records for most of Ireland.
For Isabella Smith B ditto, I found 1 record in Co. Derry.
For James McEvoy B 1813 +/- 1 yr, somewhere in Ireland, with the parents' names unknown, I found 7 records, but none in Co. Derry.
For a marriage of James and Isabella, 1833 +/- 2 yrs, I found 0 records.
For either the son Henry or daughter Bardelia, B 1834 and 1836 +/- 2 yrs respectively having parents named Henry and Isabella, I found 0 records.
The above infers either their records haven't survived, or haven't been transcribed yet. The names Isabella Smith, and James Mcevoy as well as children named Henry and Bardelia suggests they were Scotch-Irish and hence, protestant.
Protestant records are the LEAST likely to have survived, especially at these early dates. All of the protestant dominated counties (Ulster) have had their records transcribed. However, occasionally more caches are found.
Suggest you visit the ROOTSIRELAND.IE website, register (free) and either continue the search on your own, or wait to be notified as more records are added.