Star Trek Online bridge interior seating explanation

As much as I wish the devs would tell us.... they haven't so we have to guess at how this works, and... trying to figure it out for yourself is confusing. So here's an explanation centered on the Miranda Bridge.
It has 12 manned stations, how does the game choose those? mostly it's the bridge officers in you space team and ground team, BUT... that's only 9, you have 12 so three are just random.