This Thomas is the son of Thomas, Bernard's brother. So, Mariah's first cousin.
Thomas & Brigid's son Patrick is also listed. This Patrick will have a daughter, Margaret, who marries John Farrell ... PJ Farrell's parents (hello PJ!)
William, Mary, and and their daughter Mary Kate. William is also the son of Thomas, Bernard's brother. But ... oh this one is almost too hard to explain, so see this:
The townland of Cloonreliagh: