I have not had the opportunity to confirm this experiment with anyone, and I do not know the precise details or possible ramifications of using this "mod", but for your information:

There is apparently a way for your computer to temporarily download any exterior model & textures that another person online is using no matter what the aircraft is. Default or addon. Both parties must have the following lines enabled in the [MULTIPLAYER] section of the FS9.cfg for this to work, but it could save us from suggesting that people stick to using MS default aircraft. The following lines in the cfg are already present, but with 0 values. Change them to the following:

ALLOW_PLANE_MODEL_SEND=1
ALLOW_PLANE_MODEL_RECEIVE=1
ALLOW_TEXTURE_SEND=1
ALLOW_TEXTURE_RECEIVE=1


Say for example that I am using Team KBT's P-3 Orion with a third party repaint for FS2004. That's a third party aircraft, with a not included third party repaint.
Suppose then that another person is flying online with me but does not have this aircraft or repaint. If we both have the FS9.cfg lines installed, then his/her computer may download the exterior model and livery straight from my system so he/she can see it properly.

This will obviously take up some bandwidth, but it might be worth it during small events.

I have my system set up with the FS9.cfg mod ready to go.

Again, I don't know how "appropriate" using this built-in feature is, mainly because I am not precisely sure how much of another aircraft this downloads (pretty sure that it's just a temporary session thing though, so you can't keep the bird), but I just thought that it is an item of interest.
-Sean

Hopped online briefly with Fozz to see if the changes worked. No positive results unfortunately. 

I was really hoping that would work. I wonder if any of the other cfg settings in the mutiplayer section affect it.

Could have been a beta feature that was never used/completely removed.

Sorry if this sounds stupid but maybe it could require other numbers...? Sorry, I'm clutching at straws here. Thanks for finding and suggesting it in the first place though.

I bet these entries are for the direct connection between players method, when a server is not available, or not needed.

Speedbird wrote on Jun 16^th, 2009 at 2:17pm:

skoker wrote on Jun 13^th, 2009 at 6:04pm:

ShaneG wrote on Jun 15^th, 2009 at 8:14am:

You could be right. At least someone finally tried it. I've never used Multiplayer myself but I've asked begged people to try this out many times over the last few years. Always with the same result. Everything went quiet so I could only assume that nobody was interested in even trying it.

I believe it did work in the days of CFS1 & 2 but there are several drawbacks. First, everyone in the session would have to do the CFG tweak & second, it would probably cause a time lag & possibly lock up your PC.