Thank you for writing... very glad to hear from you... please write back after you read this message. I would be happy to share anyinfo that I have re McAvoys.
My gg-grandmother, Rosena "Rosa" McAvoy, was born Belfast, Co Monaghan in 1826... parents Cormick McAvoy and Ellen Keenan (sometimes written Nellie). Did not know where she was born before a month ago... she had a sister Mary and brother Thomas.Rosa mar Francis McMahon 1851 Charlottetown... 7 children born PEI. About 1869 Francis and Rosa and her brother, sister and father moved to IL... father Cormick is buried IL but no trace of her mother Ellen. All above found on 1870 IL Census, Whiteside Co, Fulton. Have photos of headstones at Catholic Cem in Fulton.
Possibly the Thomas McAvoy you mention could be a brother of Cormick? When was your Thomas born? As he was already established at PEI by 1841 that could be why they migrated to PEI 1844. Believe Rosa's husband also migrated 1844 with his family... he had a brother John McMahon (shiprigger) who I think married an Ellen McAvoy. They eventually migrated to Boston area.