So far as I know, it has never been suggested by anybody who understands how language works that "union", as applied to the bellows-blown Irish bagpipes, has any connection whatever to any political "union". That is Fakelore, not history, however much the myth may be believed by the credulous. If "sorefingers" has evidence to support his comments on the uilleann pipes, then he should certainly contact some of the Irish musical historians specialising in such matters, who would, I am sure, be glad to learn something that their best efforts have not, so far, revealed to them.