Multiple users per train in multiplayer

Greetings! I have decided to post here to ask if this is the correct approach for trying to achieve this on my own and then Submit it to N3V. What I am trying to accomplish is the ability for more than one user to be able to claim and move controls on the same train in multiplayer thereby allowing a user to play as engineer while another plays as conductor on the same train. I think it may involve editing Trainz Native script for multiplayer... I have heard however that changing even a single line in the native script will cause all native scripts to crash. If that is the case how does anyone go about changing the native interface at all? Any Support/ pointers on this is greatly appreciated.