I am not familiar with any of the names you have. Except for in the Griffiths Valuation. The John Finlay Sr. or Jr.
My ggg grandfather John Finlay was married to Mary Ann ? Their children are my gg grandfather James born 1845, who came to America when he was 20. Margaret born 1855 married a William Hughes. Also John, Thomas, Robert and Alexander. I do not have birthdates for the others.
If your John Finlay was in County Monoghan and in the Muckno Parish, it's most likely they are related. There are microfilms of this parish. They are in the PRONI. I haven't been able to see what is in them though. It is a charge to have them do research for you. Too much.