When occupying a newly-conquered territory, a fun thing to do to is to start shipping off newly-encountered species to other systems in the hopes of growing that population type and getting its collection bonuses. Or, in the case of Cravers, shipping them to some system you don't care about. The reverse is also nice; being able to send minor populations to a newly-conquered, low-occupancy system for "seeding".


However, the player does not yet have full ownership of the system; the population considered themselves "occupied" rather than happy cogs of the empire. Large happiness/ownership rate penalties should be applied when moving population units to/from occupied systems.


As a fun aside to this idea, I'm fairly certain that the forced relocation of peoples to/from occupied territory is considered a war crime. Perhaps a low-mid-level "Empire Development" tech should be needed to find the legal loopholes to allow the manipulation of population units to/in occupied territory.