Hi!
There are many ways you can do this, here are some options:
For example you can create empty game object and parent all enemies to that object, then use Send Event action and check children if you want to send to them.
Other option can be to Broadcast All and to send event to every FSM object on the scene.
There is more complicated way of doing this with Array List where you can use Array List Find Game Object By tag, and then you can use Array List Get Next, and loop through items by storing them as game objects and send event to every item until you send event to all objects.
I hope this can help
Cheers!