Hi Sue, I see you are still chasing down Ellen Mahony = Jeremiah O'Neill. Since I last saw any of your posts it sounds like you have scraped up some more clues. Good job!
Cahalane and Cohane have a strong presence in Kilmacabea civil parish. I am working on that tithe applotment right now. I have a direct Cahalane ancestor myself from that area. Mahony and Deasy are somewhat tougher, as they pop up everywhere.
If you have specific names (Christian and/or surname) I'll be happy to look through the Kilmacabea tithe data. I also have the TA for the parishes of Myross and of Castlehaven which I have not yet transcribed.
Kilfaughnabeg (which I have online) has a clump of Keohanes in Kilfinnin.
If you have any information on the relationship of a Cahalane to Ellen M or Jeremiah O'N please specify that too. (Somebody was a baptismal sponsor, witnessed a wedding, or was a cousin, aunt, uncle, etc) I may have Cahalane contacts who might be able to tell me something. I can always email and ask.
You want something looked up in TAs, message me through my profile.