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You don't mention the religious denomination for the family but I assume Church of Ireland? The C of I records for Kilmacow are not online and are available locally. From this link http://cashel.anglican.org/?p=3739 it does not appear that the church in Kilmacow is active. You may want to contact the Kilkenny church and see where the records are held.
I also did a search on the Tithe records for Co. Kilkenny and there were many Barrons listed