How to stop friendly-fire between enemies

I’m working on a game for practice and learning porpuse. I want enemies to attack my player (it’s working) but if they are next to each other they damage each other too. I have my character done in a BluePrint Actor and the enemies are 2 childs of that BluePrint. I tried to work in “Apply Damage” node filtering by “Instigated by” but I can’t make it work properly.

If someone need to see the BluePrints that I have just ask and I will post screenshots of them.