Suggest you search Canadian immigration and naturalization rcds to find their DOB/DOM, POB/POM.
Currently, searchable Irish civil rcds end in 1920. NI rcds are kept by the Public Records Office for Northern Ireland. Google PRONI to reach its website. I believe it has a 100 year rule before it makes rcds available to the general public. However, since you are likely a direct descendent, they may comply with your request.