My great great grandmother (birthdate probably in mid 1850's) was Catherine McMahon. She married Patrick McNamee of Cloghfin and gave birth to 8 children, between 1877 and 1891. Most of them, including my grandfather James, emigrated to the NYC area. The oldest son, Patrick, inherited the farm and has many descendants in the Cloghfin/Sixmilecross area. So your g-g-g-grandmother Bridget may have been a sibling of my g-g-grandmother Catherine. I have a photo (poor quality) of Catherine if you're interested.
FYI, I believe Catherine Mc Mahon was Patrick McNamee's 2nd wife. His first wife, Catherine McElduff, died after giving birth to 2 children before 1877.