I have Player 1 and Player 2

I am using Json to send and retrieve player data between the client and the server, but when another player logs in, and is in the same map, how would I send that data to both players to update the graphics engine to show there are 2 Players on the map?

About my game

• it is a 2D RPG tile based game
• it is 24x15 Tiles
• it is Real time Action
• it should interact anywhere between 10-150 ping
• players interact with each other when in the same map and can see each other moving around
• the game world is persistent, and is saved when the server shuts down

Right now the server just sends the player Only their information which is inside a Json Object

Here is an example of what I am talking about

If you notice there are 2 separate characters in 2 separate clients, but they are running on the same server. I am trying to get them to show up on both clients, but I don't know how I should accomplish this. Should I send it as an added value in the Json object?

Also what is the name of this process so I can look it up and find more info on it?