hi Frank ... your mention of your Cork parish database have got me thinking that it could include mention of ggg-grandmother Catherine Nevin who was born around 1838, her father was Andrew.
If you have a minute could you have a look for Catherine or other Nevin family members in South Cork.
All I know about her early life is from her marriage cert in 1854 in St. Michael's Chapel, Parish of Finn Barr (C of I), her address is given as simply Blackrock - so I am hoping she was also born in the area.
thank you,
Shane