Alif,
Thanks, I'm glad you like the programme. True multiplayer is not currently possible, although it is on my list of features I'd like to add.
What you can do is have one person running the 3d simulation with Bridge Command, and another person running the 'Map controller,' which can control the other vessels in the simulation (by setting their course and speed interactively).
So you can have a simulation where the ship's pilot has to interact with vessels controlled by someone else, but as yet, this can't be done with two people each 'piloting' their own ship.
If you're interested in the current Map Controller, and you need any help setting it up, let me know, and I'll try and guide you through the process. (There's also a guide at http://www.bridgecommand.co.uk/Doc/controller.html (http://www.bridgecommand.co.uk/Doc/controller.html) which may help.)
James