Steve
A bunch of us have asked in the past about assigning members in and out of teams and you didn't want to due to mechanics/programming issues. However, how about this?
Treat a team like a task force command staff, so you have a team leader and then four members under them. You could then have multi-skilled teams and you can pull out experienced members so they can then lead their own teams. It also leaves the members subject to all the normal officer rules like health, promotion, auto-reassignment, etc.
The reason I don't want flexible teams is more a game design/mechanics issue. At the moment, placing people in teams has a downside. You lose the officer who is transferred to the team and you also reduce the overall officer pool, which in turn reduces the number of available senior officers. You also need to decide whether to form a team with the officers currently available, perhaps using up 2-3 good officers and 2-3 mediocre ones or wait to see if better officers graduate.
If officers can be moved in and out of teams, there is no downside. You could have as many teams as you wanted with no penalty and you would never have to wait. It takes away a couple of important game decisions.
Steve