In light of several requests including comments on my youtube video (http://www.youtube.com/comment_servlet?all_comments=1&v=OGSmKR0OHWY), I've (done a U-turn and) decided to release the U-Drive-It Jetliner Mod. The mod replaces all UDI Planes with commercial jets.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fi597.photobucket.com%2Falbums%2Ftt56%2Fjoelyboy911%2FUDIMod.png&hash=577d9e71bb77809c222cfecd6cea339cb88a8478)
The issue (mostly a cosmetic one) is that each menu icon appears twice. I've tested with empty plugins to make sure that there were no duplicates. If anyone knows a way to prevent this from happening, I would be extremely grateful to know it.
I also seek to know how to remove Area 5.1/Fire Dept. Landing Strip/Landing Strip from their respective menus, because they would look extremely bizarre with these new planes across them.
Many thanks for any information you may have.
I suppose your mod includes a copy of existing exemplar files? The same problem arises when creating a NAM plugin that modifies the original icons, such as the "NetworkAddonMod_Custom_Highway_Menu_Plugin_Optional.dat". What you have to do is providing another ID for the new icon, and make an "invalid" exemplar file with the original ID. It will override the in-game ID, and doesn't display an icon anymore (this could also be used to remove a certain transit/UDI icon from the menu completely). I suppose a similar method could be also used to remove any lot icon from the game.