* There's a region between Federation and Cardassian space. In it, some planets have been settled by Federation populations, some by Cardassians.
* Until the Cardassian government gets a bug up its ass about border security.
* The Federation agrees to give up its planets, all but abandoning its people to Cardassian rule.
* Some of those people have a problem with that and a resistance movement forms.
That seems to me like a legitimate grievance?

