There has to be a better way to do this. If you have a team of 5 players and you don't want any of them to have shared control options with the others, then you would have to specify each alliance combination.
make player 1 treat player 2 as an ally with shared vision
make player 1 treat player 3 as an ally with shared vision
make player 1 treat player 4 as an ally with shared vision
make player 1 treat player 5 as an ally with shared vision
as well as...
make player 2 treat player 3 as an ally with shared vision
make player 2 treat player 4 as an ally with shared vision
make player 2 treat player 5 as an ally with shared vision
continuing..
make player 3 treat player 4 as an ally with shared vision
make player 3 treat player 5 as an ally with shared vision
and finally..
make player 4 treat player 5 as an ally with shared vision
Seems like a lot of statements for completing this simple task. Isn't there any way to disable sharing units within a force?