As one leader to another, I would strongly suggest parking a fleet of no less than 10 ships over a target planet and allow the citizans time, (10 turns) to come to their senses and welcome you as the leader of their race. Of course, it would be to their benifit to build temporal (if you have temporal technology) vacation sites on one planet within a newly aquired system. If no temp tech, the urban pacification centers on each planet would be of great benifit.
The may take some time, but time is on your side.
Or you could do what I do, and upload the ungrateful things up to a cargo transport and introduce them to oblivion via a rapidly evacuating atmosphere. Then simply abandon the planet but leave the tech and buildings.
Best of luck. May we meet in battle someday.
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