This is the easiest method, you can do this for however many instances you want here is what I would do.
1.Change the 127.0.0.1 to 127.0.0.2 in Proxy.cs and ParseServerDataCommand.as and keep both files.
TcpListener should be working for both.
2.Build & Run Both Client(s) and K-RELAY(s).
https://imgur.com/a/k23XCC7
Client (ParseServerDataCommand.as)
K-RELAY (proxy.cs)
If these don't work I would try changing the ports and ips.