The link below is long and perhaps complicated, but it is the link to a site that specializes in ancestor searches. While it is a membership site for the purpose genealogy and carries a month to month cost of less than $15 USD, you can get a 14 day free trial.
I personally used the site to find out that my second great grand father was in the Civil War and my 2th great uncle was a surveyor on the payroll of XXXXX XXXXX when he set the physical measurements of Kentucky here in the US.
If the link below is BLUE - just double click on it and the site will open in a new window. If it wont open, simple go to the www.ancestry.com site and type Brien, Stephen in the search window. I got a list of his specific name as well as possible spellings and other info. I have enjoyed the time looking for family and have learned a lot.
While the site is owned and operated by the LDS (Mormons) in Utah USA, it is not necessary for us to be members of the Latter Day Saints.
http: //se arch.ancestry.com/cgi-bin/sse.dll?gl=ROOT_CATEGORY&rank=1&new=1&so=3&MSAV=0&msT=1&gss=ms_f-2&gsfn=Stephen&gsln=Brien&_81004030=1855&msdpn__ftp=Kilmaine%2C+Clareen%2C+Co.+Offaly%2C+Republic+of+Ireland&uidh=6p5
Hope this helps.
Please let me know if there is anything else I can do to help and please refer others to me by name - Webjunki