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RC records for Strokestown/Lissonuffy parish start in 1830.
The 1825 Tithe listings for the parish show two Neil records so there may be a connection.
The 1855 Griffiths Valuation head of household listing for Lissonuffy parish shown three O'Neill records including a James O'Neill in Trilia (Martin) townland.which is where the two Neils in 1825 lived. http://titheapplotmentbooks.nationalarchives.ie/search/tab/results.jsp?surname=neil&firstname=&county=Roscommon&parish=lissonuffy&townland=&search=Search
I checked the subscription site Roots Ireland and there were many McNeal/McNeil/O'Neil/O'Neal baptismal records in Strokestown parish. There were 32 baptismal records in the 1830s. Did your James return to the parish?