First of all, have you gotten the civil birth record for John Boylan, b. 1908, son of Michael Boylan and Mary Ann McCarthy? The actual civil birth record will identify his specific birthplace in County Westmeath or Ireland.
You can order the civil birth record from the Irish General Register Office http://www.groireland.ie
and click on "apply for cert".
With the exact birth location you can then search the 1911 Irish census microfilm for that location to get information about his parents such as ages, the names of other siblings who were born by then and their ages, etc. The Irish census records for 1901 and 1911 aren't as yet computerised or available online. They're available on microfilm for search on order through a LDS Family History Centre.
You can then also order the other siblings civil birth records from the General Register Office with their dates of birth.
Michael's birth might have also been included in the civil registrations of births. However, you'd need to know his date of birth and parents names to try to find a civil birth record for him if his birth was registered.
It would be extremely helpful when you post messages if you could post:
a) ages/dates of birth
b) parents names
c) locations in County Westmeath where the various family members were either born or lived. There are nearly 1,500 towns and townlands in County Westmeath.
That information is critical not only for anyone to make possible family connections with your line but also to identify what research sources might have survived in County Westmeath (or Ireland) that may include the family's records.
There wouldn't have been just one Boylan, Murray, Lowe or Fitzgerald family or family line in County Westmeath.
Irish civil registrations records aren't available online nor are they computerised.
There are no surviving census records before 1901.
The locations would be the town/townland, civil parish.