a composed song is owned by someone it need their permission to alter it, and certainly to significant;y alter its meaning that is the law,

It is in some jurisdictions and not in others. Parody is permitted unconditionally in most places (I think France is an exception). In general, the original composer will still be entitled to payment when a modified or parodied version of their song is performed.

But law only follows ethics in part. Refusing to acknowledge a composer's nationality or ethnicity (as a lot of people in the wannabe-Irish music scene do when the composer is English) is repulsively bigoted, but I doubt there's a law against it anywhere.

(Wouldn't it be great if there was a law we could use to ban English D/G melodeon players from mutilating the Bluebell Polka by leaving the C section out? Or to compel Irish musicians to play Mrs Macleod of Raasay the right way round, in the right key and with the right title?...)