Rita,
In exploring the marriage witnesses; and then trying to locate their marriages to discover a father's name, while that did not work, here is what I found. Assuming that the witnesses were siblings - Celia Keegan is a witness to Bridget; and her marriage I believe anyhow, in 1863 to Michael Carney, shows Mary Keegan as a witness. Then Mary's wedding in 1858 to Michael Frain has a Martin Flatly as a witness. I found these records on the paid site Roots Ireland....I believe the surname was transcribed incorrectly as they show it as Reegans, Regan, etc....On the original document it is difficult to decipher between the upper case R and K. When I viewed the Griffith's record with the many Keegans, there was also one person named Reegan - I wonder if that was an error in transcription too. You know better than I if your ancestors were Keegans or Reegans! Generally, I believe the surname Regan to be spelled either Reagan or Regan.
Regards,