My 3x ggrandfather, John Armitage, bought land in western New York state in 1816 and in the 1820 US Federal Census there are several children listed. At least 2 of the children are his sons, Joseph, born 1818 and John B. born 1820. There is a passenger list to New York City in 1811 that lists a John Armitage, from Tipperary. I can't be sure this is my John, but if it is, then he married Fanny in New York, either in Ulster of Washington County. One record shows Joseph born in Washington County.
So, my John can't be the one listed in your link. There are just too many Johns and Frances/Fannys to sort them out.
Thanks for your reply ant the inks.
KaParcero