Thank you very much for your post. I will certainly go to the Irish Family History Foundation web site.
I found the marriage of Eugene CONLON and Margaret BRENNAN, married 11 May 1815, in the Boyle Parish Records, Family History Library microfilm 989743. The entry was written Eugenium CONNELLON and Margaritam BRENNAN. Witnesses were Patrick BRENNAN and Johannes LEONARD. The baptisms of offspring Patrick, John, Catherine and Thomas were on the same microfilm.