Quote Originally Posted by Deus Ex
ahhhh - so in order to "Foment" rebellion, they just have to sit there in the province then??

DE
Yes. The more stars they have the better they are at it. Since the patches, only the spy with the most stars has an effect - so spamming multiple spies into your opponents province won't increase the likelihood of a rebellion.

If they sit in one of your provinces then they help avoid rebellions, but again it isn't something you can expicitely order them to do.