Thank you for very much for this information. i have established the James-Michael-Thomas generational link. It would appear that Michael's birth is off by 10 years between the marriage and subsequent census info, it appears that he was actually 19 rather than 29 when he married, he being born in 1841.
It would appear that the connection is through James born 1806. My ggg grandfather Charles had 2 known sons Patrick (my line) and Dan, they both started their families in the 1830's, so I would see them as possible brothers to James. there were also 3 O'Connor families on our side of the parish here in Co.Clare Ireland in the 1820's. No records of a marriage though, and the only records of a James Killeen having a child baptised are in 1839, a daughter Mary and he was married to a Jone Meany. Michael born 1841 was born in Ireland!, they must have left the parish and lived elsewhere prior to emigrating. Also James is not a common name in our family. Note all Irish census records from, 1810 to 189? were destroyed in a fire during the 1920-21 war here.
Thank you very much for information, interest and kindness in providing. I think connection with James b1806 may have to go as a strongly suspected connection connection for the time being.
All the best