Tracing family connections in Killarney

I am trying to find out if there is a connection with the John Brien and Mary Sheehan to my ancestor John Daniel O'Brien. I used my DNA results to trace back Charles O'Brien from current relations to the baptismal record attached here. Using DNA matching, I do have both O'Brien and Sheehan matches. 

 I am trying to find out if the John Brien and Mary Sheehan in Charles' baptismal record also had another son around 1817 whose name was John or Daniel O'Brien. I would also like to know where they lived around that time if possible.