Looking for information on John Joseph Hill ( born 1838 ) and his wife, Ellen Olver ( born 1838 ) from Drumachose, Derry, Ulster who migrated to New York in 1867, I have found their family names in the "tithe applotments" of 1826 but nothing else.
I have found a marriage for what appears to be your couple in Ireland but it was in 1868 and in Co Armagh, not Co Derry. They married in Armagh Register Office.That should help you trace the Hill family who were farmers, and usually fairly easy to find. Labourers families can be a bit harder.
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_re…