I have a idea on how to do it;

1. Use a transport and move it to a friendly planet lacking in population (transport is lost in the process), then a option to start a population trade route is given. Population between the two planets can then be moved around once a turn for easier empire management and saved time for those that like to give new planets a kick start. Also planet growth can be shifted from one to the other.

HOWEVER, since this idea is brilliant and dangerous to the balance of the game, I have a disclaimer; a. It takes one turn per tile to send the population to the planet or one turn and grows with the distance, sounds fair right? b. Multiple planets can be linked but can only receive population once per turn. c. maximum is 2.5b per turn, a standard transports load. d. No more population than food can be given. e. The sending planet has stalled production for that turn because relocating billions of people causes chaos. LOL

2. Awww! The last slave died in the slaughtertorium, what will we do now? Have no fear more population is here! Sell people to other races for money or buy them yourself using a trade ship (black market?*). The applications can be war profiteering (selling population), income (selling your population growth), ideology (give me a minute and I'll think of how it effects it... ), and strategic purposes.

3. (My final sales pitch) If done right, this will save hours of time on medium and larger maps over the course of a game and make new planets on huge empires easier to manage while increasing the turns per hour margin.

Thanks for listening.

DARCA.