Festy as a first name and Festy Flynn in particular in Kilbegnet

It has been a while since I posted about my ancestors James Flynn c1816 & Bridget (aka Bidy) Walsh 1817 and their known family Brtidget 1844, John 1848 & Mary 1851.   Recently using FindMyPast's new Irish Records Transcriptions I came across the family in the 1851 Census in Co,Galway,Kilbegnet with the addition of a new child Festy Flynn born c1841.   I had never come across the name before and at first thought it was a mis-transcription, but checking the 1901 Census -just for the name - I discovered a good many Festy first names (all as far as I could tell male) and shown mostly (recalled from memory) Clifden, Galway - part of Connemara.  So the name was correct but I have not heard of a Festy Flynn in the family. I can trace all the others and  the daughter Bridget, became my Great Grandmother in Birmingham, UK.    I know of John's family and that Mary (1851) died as a child, but no Festy then or later.

I also had doubts about Festy because if 10 in 1851 his birth year of 1841 is one year before James & Bridget (the mother) married in 1842.   Attached to the 1851 Transcription was an image of a Ministry of Housing (UK) check in 1920 on the family in the Irish Census and a query against Festy with the ?Marriage 1842 ? 1839.   I presume this may have meant they found a marriage (i would think for James,or perhaps Bridget or neither (perhaps legitimising an out of wedlock child?).  I cannot find a birth/baptism for Festy (the name gets rejected) and without using it, nothing remotely applying to a child that could be Festy.  I have also been unable to find a marriage for a James Flyn other than the 1842 one, but that is ongoing.

My dilemma is there was a Festy Flynn aged 10 in the 1851 Census with James & Bridget's family. As there are no relationships shown so who was he;  was he perhaps a cousin?    The family moved to the UK sometime after 1851 as Mary died in Birmingham c 1853.  But no Festy. Did he die in Ireland or remain in Ireland (remember he was only 10 in 1851) perhaps with his Grandparents?     Can anyone give me pointers how I can set out to find Festy and prove his birth and check whether his father was previously married and Festy was born.  Perhaps she died giving birth and James remarried Bridget.

Sorry if I have rambled on, but I did not want to miss anything out.    I shall continue on my own of course but as Ireland XO was most helpful a few years ago to help me trace my Flynn ancestors, perhaps someone can see a way through this time.  Many thanks - Robert (Bob) Spiers