Sandra,
Thanks for the info on the other O'kanes; John and Daniel and Francis.
I found a baptismal record for Agnes (illig)baptised February 1871 per St John's RC Church records Coleraine. This can be accessed on the website of the National Library of Ireland-all now digitised.
Agnes is the daughter of John Kane and Matilda Mc Carron per the record. This lead me to get their marriage cert from the GRONI website ( General Registry Office Northern Ireland). They were married in St Johns Killowen, Coleraine on 3rd April 1871. He is the son of John O'kane of GLENHALL and she is the daughter of James Mc Canon of Woodstown, Coleraine. A farmer and a labourer respectively.
This is the John and Matilda Mc Carron documented by you and by variouse family trees.
The Glenhall connection is a strong one as there was only one John O'Kane in Glenhall in 1859 per Griffiths Valuation. It would appear that Daniel and Francis were with James in 1870 but later in 1875 Daniel went to live with John and Matilda. It explains why John was in Glenhall when Mary (Dempsey) died in 1870 per my previous post.
I am happy that the burial plots and the census info puts these 4 as more than likely to be related and to be from Glenhall.
Thanks again.