Клиент-сервер. Как в многопользовательском чате реализовать личные сообщения - C#

                Console.WriteLine(Func.ToDateTime() + "Server started.");
                TcpListener listener = new TcpListener(5000);
                listener.Start();
                while (true)
                {
                    
                    TcpClient client = listener.AcceptTcpClient();
 
                    StreamReader reader;
                    Console.WriteLine(Func.ToDateTime() + "Client Connected.");
                    StreamWriter writer = new StreamWriter(client.GetStream());
                    writer.AutoFlush = true;
                    reader = new StreamReader(client.GetStream());
                    Thread thread = new Thread(new ThreadStart(delegate()
                    {
                        
                        string message = string.Empty;
                        while (true)
                        {
                            try
                            {
                                message = reader.ReadLine();
                                writer.WriteLine(Funtions(message));
                            }
                            catch { client.Close(); Console.WriteLine(Func.ToDateTime() + "Client disconnected."); break; }
                        }
                    }));
                    thread.Start();
                }