That depends on what you are trying to do and on the enemy itself, but in general you will need to:
- First add them to the 'Player's Faction'
- Second 'StopCombat()'
- Third 'EvaluatePackage()'
But as i said, this depends on the enemy, for example:
- In the mod i recently released some of the enemies have either a "Hunting Player and Allies Package" that neither one of the above will ever work. The npc will always 'Hunt' the player.
- The enemy is been scripted to "Always" be in a state of combat with the player and his allies.
So, the approach above will never work on this npcs no matter what you do, the only way that those npcs can be affected is, if they are directly modify in CK.
So, this approach is not 100% reliable since i'm sure that i'm not the only one that does this.
If is intended to work only in your mod with your npcs, then it can be 100% reliable.
* But if this is the case, then a simpler way of doing this is to just remove from those npcs their hostile towards the player faction.
I hope it helps.