I'm not sure if someone had ever mention this before, but I think I've figured out how to control AI drivers to sign whatever team you wanted them to sign in the MyTeam mode, at least to some extend because there're still some random elements which cannot be completely eliminated.
First, a few concepts needs to be said before getting into the main part:
This is only for MyTeam mode
The method is about eliminating options
Always backup your save file so you can try agai