Hi Pat,
You could try posting as much information regarding the individuals you are researching. The more information you post, the more likely it is that one of our olunteers will be able to assist you. Remember to include what sources you may have checked already.
If you haven't already you could try checking the land records called the Tithe Applotment Books (1823-38) or the later Griffith's Valuation (1848-64) for Thomas or his relatives.The Tithe Applotment Books (1823-38): Microfilm copies of the books for all of Ireland are available at the National Archives of Ireland (NAI) http://www.nationalarchives.ie/genealogy1/genealogy-records/tithe-applotment-books-and-the-primary-griffith-valuation/ or the Church of Latter Day Saints (LDS). Griffith's is freely available here: www.askaboutireland.com or here: www.failteromhat.com Failte Romhat has lots of other useful links you could try looking at.
Do you know much about their emigration? Dates, the reason why they left, etc.? Generally more information was given at the port of arrival rather than the port of departure. If you knew which city they arrived at (e.g. Liverpool), this could be a good place to find more information.
All the best.