Not sure where this question would best be posted, so...

Is there any way to create fixed starting locations on a map?

Let me explain in more detail:

I’d like to set up a large game where 3 human players (Me and 2 friends) start in the same star system so we have a single initial choke point to defend (once we secure the system of course).

I’d like it to be in a game with several large star systems. (So our game will last us the better part of a Saturday).

And (if possible) I’d like it to be in a game where teams can be changed (thus encouraging the AI to team up against us of they so choose.)

Is there a way I can accomplish this using a “randomly” generated map?  Or with one I create myself?

Thanks for any input you can offer!