Hi,
Love the name 'twistedbranches'.
Any chance some of your Brennans came to the US, particularly Schuykill Co., Pennsylvania?
This area was heavy with coalminers. My Muldowneys came from Castlecomer, also with many other names of the area, some of them came pre-the famine era. I know, from my research, the hills of Schuylkill Co. were alive with plenty of Co. Kilkenny names. I have some Brennan names in my maternal grandmother's tree. If you need to search for any family members in the US, this would be the area to start with.