The bug has bit
When the records exist it's straight forward enough to step back from your parents, grandparents and so on but moving sideways isn't so easy as you don't have the younger generations names to work back from.
You need to work with what you know and expand from there.
Ideally you need to find marriages for the siblings, you have their first names and father's name hopefully the church record will include the mother's name as well so you can be sure it the right one.
The danger is cousins with the same names may live in the area to cause confusion also marriages usually happen in the brides parish so if any of the men married a woman from another parish you may not find them.
Witnesses can be a good clue so always take note of them.
You might also want to extend your search to Newspapers, a death notice can help identify relations and sisters or aunts marriage surnames.
My great grandmother's funeral report gave her 3 brothers names and her home address, pure gold.
Petty Sessions court cases are also useful, more for adding a bit of flesh on the bones but you never know. Almost everyone ended up in court at some point. My great grandfather was up in court for fighting with his dead daughter's sister in law, which helped me pin point the husband's family.
https://familysearch.org/search/collection/list/?page=1&countryId=1927084Also have a look at the other records the National Archives have
http://www.genealogy.nationalarchives.ie/The more familiar you get with the family names and the area they lived in the pieces of the puzzle will start to fall into place just take your time, once you have everything on the immediate family you may find you have gathered up names of relations that can be followed and connections are made to some of those other families you have seen in the Census.