David: I am working on Timmins line that emigrated to Canada in 1820 and at that time 3 brothers - James, Henry & Andrew left Ireland. Andrew was b. 1800 and UNK for the other two. My information says they were from Cty Fermanaugh and I do not know if that would include Dublin or not.... I am a Canadian myself and not up on my Irish geography.
I will let you know if I come across any further info that may help you.