I have conquered 2 planets from the same enemy civilization about 40 years ago, and have been dealing with a homelander faction ever since. The faction's only demand is for me to return the planets to their original civ. As an individualist civ, I'm unable to enslave, purge or relocate the hostile pops, and I've sunk literally thousands of influence and energy into bribing their leaders and suppressing their media presence, as well as all 3 tiers of the integration campaign. The pops themselves are at 35-50% happiness due to a -20% happiness modifier "Alien Overlords". I've tried appointing a governor of the same race as them to a sector just all their own, but apparently that doesn't work. How do I get them to properly integrate into society?
I had a similar problem. I vassalized my rowdy neighbor and integrated him doubling the size of my empire. Only problem was they were a bunch of xenophobic slaving ****s. Try this;
- Click on the rowdy planet and go to the planet summary screen
- Check out the edicts list.
- Happiness and Ethics Divergence.
Happiness will decrease the likelihood that pops join a faction. Ethics Divergence will change the traits of their pops over time. Usually towards your main race's traits.
Give it a few years. Keep pumping up happiness. Change government types if it increases happiness or ethics divergence. If all else fails, station an army there and wait for the revolts. When you crush them, they'll shut up for a while.
Hope this helps!