Denief, Kilkenney

Hello! I've been stuck on this brick wall for months now. I live in Nova Scotia, Canada, and I'm tracing my ancestry in Newfoundland, and it's Irish connections.

I was always told that my maternal great-great-grandparents immigrated from Ireland to Newfoundland, and that they supposedly originated from Waterford:

James Sullivan (b. 1876 - d. unknown) and
Margaret Sullivan (nee Collins, b. 1880-1977)

However, local records state that they were both born in St. Kyran's, Newfoundland, but their nationality is listed as Irish in an early census there. Their granddaughter, who is my grandmother, insists they both had the strong Irish accents, and she suggested that religious conflict there may have led them to leave for overseas.

Further tangling this murky info is the fact that James and Margaret Sullivan disowned their daughter, Mary Margaret, for marrying outside of the Catholic church, and forbade the family from talking to or acknowleding her, so my grandmother was not close to her own grandparents for much of her life. The resulting rift created dysfunction among the family, and info is limited for this reason.

What I did find while tracing records is an Irish connection that goes further back than my grandmother believed:

John Collins (b. 1797 in London, England, d. 1864 in Newfoundland) and his wife,
Honora Collins (nee Denief, b. 1810 in Kilkenny, Ireland and d. 1891 in Newfoundland)

They are Margaret's paternal grandparents. John's parents, John Collins and Bridget Oates apparently originated from Ireland too, but I'm unsure of which county.

Does anyone have any info on how to locate their parish and vital statistics, as well as potential parents? I take it Denief is not a common surname in Ireland, but I've found very little else. Any suggestions or help is appreciated!