My mother used to occasionally pester me about joining the tribe but they only do descent matrilineally so I never bothered.
I just checked and they don't specify matrilineal descent, just lineal descent. Could it have changed? My sister's husband is a member of the Blackfeet tribe by adoption. He lived with them for two years in Montana and they gave him membership after that. He has the feathers and the whole kit and caboodle :) It's actually really lovely watching him when he does his offerings and prayers to 'Mother Earth' and 'Father Sky'.
I don't want that info shared with governments....
Why? On a point of principal? Or do you think they'll do something sinister with it? I can't imagine what that could be. Sod them. If you're a Choctaw, you should know about it.
a hero's welcome in Ireland
You'd get that anyway. Just tell them Atch sent you ;)