Not sure about topic name.
I'm using EE MMO Source, client side network.
And currently find a way to send interaction to specified obj, NPC, or player in different client, like healing.

Unlike sending client's data.
I want to send interaction between obj, like Player A healed Player B and NPC C.
Player A sending heal value to server, but what data should I send to determine Player B and NPC C, to let owner of Player B getting healed.

If you want PlayerA to heal PlayerB, and the server to recognize who you are trying to heal, keep an ID that is synced with all clients, upon cast send the action + id and there your server can recognize of which clients are getting healed.

That's straight forward,

I added UID to Chrs which will be randomize from server then send to an object upon creation.