Multiplayer Co-pilot FS9

I think it would be cool to be able to link up FS9 with a mate and "share
the same aircraft" so to speak. Have the ability to both be able to control
the aircraft and its systems. Doing a flight in one of the heavies and
having a co-pilot there as a resource to set radios, lower/raise the gear
and flaps would be cool I think.

It would also be advantageous if one wanted to teach another a procedure, or
just to fly in general. I know gunship 2000 has the ability to have a pilot
and gunner and the same is true of IL2.

How hard would it be to implement in the existing sim? Would an add on do
the job or would it need to be written into the original program so to
speak.

Anyone know?

Scet