Python websocket, is there a way to intercept a request made by another user?

Question

I was playing with mobti, and I noticed that when I add an user what I'm really doing is sending a json with that user. See follow example.

Json in the request.

{"type":"mob:update","mob":[{"id":"v63ghnghgn8","name":"test2"},{"id":"qlxy16bl9q","name":"test 1"},{"id":"zxu28bb3ar","name":"test4"},{"id":"03kys4hqrjmm","name":"test 5"},{"id":"w9osegszlzm","name":"test 3"},{"id":"od6hattxo3","name":"test6"},{"id":"d972agvwux","name":"test 7"},{"id":"y65txgk19p","name":"example stackoverflow"}]}

So I was able to do an script in python to send a long update with a lot of users.

url = "wss://mobti.me/example"
ws = create_connection(url)
ws.send(json.dumps(data))
result =  ws.recv()
print (result)
ws.close()

Being data a big json with a lot of names.

So now, here's de question, I was wondering if another user send a request with a new data, could I intercept that request? and how? I'm interested in intercepting the request and sending a new one. (It doesn't matter if I can't reject their request). Notice that this website isn't mine, so I can't intercept that request from inside (and that's not what I'm looking for)

Thanks in advance!