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One minor bit of information. From the children's baptismal records, John and Bridget were living in Carrow-Cloughty townland in Crossmolina civil parish. The 1855 Griffiths Valuation head of household listing for the parish shows a John Walsh and also a Thomas Walsh leasing land in Carrow-Cloughty. https://www.failteromhat.com/griffiths/mayo/crossmolina.htm The John Walsh may be the john who died in 1859 but the Thomas Walsh could be his father or another relative.