title: Send massage to group devices in Firebase Cloud Messaging
body: <p>I am building a chat and I want to send message in FCM to 1000 clients in a group. The message would sent from client to group of 1000 clients (the message not pass through server). I can use the topic method, but if I want to remove a client by the group admin it's not possible. Anyone can propose a solution?</p>
  
  <p>Help me please.</p>