[General] tell units owned by player NOT to attack units owned by other player

[porker7]

I know this seems like an obvious question. I am trying to make an allied player but one that does not share vision with the other players.
I cannot just put this player 5 (the invisible ally) in the same force as players 1-4 (real people) because the force that 1-4 are in shares vision so they would see this ally. How can I tell the computer player 5 not to attack units owned by players 1-4?

 

[Daffa]

Trigger the alliance on map init. Player - Set Alliance.

 

[porker7]

yeah that did it, thanks!