I think you'd need to create a map using galaxy forge. In that you can assign a home planet to a specific player. Im not sure if you can assign them based on teams, so at the most you'd have to have the order of joining the way the teams would be set up.

Yea, I am making these in GF.
As Kittrell stated, even when setting up home planets, there seems to be randomization as to where you actually start off once the game gets going.

Now that you mention it, though... I seem to recall something about "team" in the players editing screen. Let me go tinker around with that for a bit.


///edit
After some quick testing, this seems to do the trick!
In addition to myself and an AI opponent starting off where expected not once... but three times, it also sets up teams for players automatically when creating a game.

...have I mentioned recently how amazing of a job these guys did on the UI and features for this game? Just thought I would again.

Thanks for the mind spark!


For anyone looking to figure this out as well:
EDIT > Players
Click a player name to edit
Set "Team Index" to 0-9

Indeed.
After testing with larger scale, it would seem there is still a bit of randomness when it comes to actual placement, though teams will at least stick together. Additionally, it may actually switch up which teams go where, as long as teams are even.