You can do it in World of Warcraft, should be doable in BNS. It's called Multiboxing and googleing for a Multiboxing software brought me to http://www.hotkeynet.com/ .
Not sure if it works or if it's full of viruses, but that should give you someplace to start atleast with either the software or the name.
I understand that this is a program for duplicating keystrokes (script) from one computer to another? and if all clients of the bns are running on one pc, how to duplicate pressing one key to all windows, you can even not simultaneously, but with a large delay.