If you haven't already - You could try checking the land records called the Tithe Applotment Books (1823-38) http://titheapplotmentbooks.nationalarchives.ie/search/tab/home.jsp
or the later Griffith's Valuation (1848-64) http://www.askaboutireland.ie/griffith-valuation/
or the Church of Latter Day Saints (LDS) https://familysearch.org/
Failte Romhat has lots of other useful links you could try looking at ). www.failteromhat.com
Do you know much about their emigration? The dates, the reason why they left, who they may have travelled with?..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, New York, etc.), this could be a good place to find more information.
Remember to post as much information as you can with regard to the people you are researching. The more information you post, the more likely it is that one of our volunteers will be able to advise or assist you.
Also include information concerning which sources you may have already used so others may further your search.
Please be patient - as our programme has only begun to rollout across the island of Ireland and volunteers in some areas may not yet be organized.
Ireland Reaching Out