This is an important feature or issue needed for populating staged missions.
When you click to assign or unassign a pilot from the mission, you should NOT be able to assign someone who is already in flight.
If you are already in the mission, it gives you an error. But it allows me to select other pilots who are in flight on either countries.
This is causing me issues, because I am clicking the wrong people on accident. It may cause crashes if I select someone on the opposite country.
