Hi
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.
Church of Ireland parish registers for the period up to 1870 are public records. Registers are available for about one third of the parishes, however many were destroyed in the Public Records Office in Dublin in 1922. Most are still held by the local clergy, although some are in the National Archives of Ireland and others are in the Representative Church Body Library in Dublin. A list of all surviving registers is available in the National Archives. http://ireland.anglican.org/about/42 and http://www.nationalarchives.ie/.
A good link for finding information regarding Catholic church records is http://www.irishtimes.com/ancestor/browse/counties/rcmaps/cavanrc.htm
Remember to post as much information as you can regarding 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.
Regards,