I know a way to copy a large groups of structures or just a few structures from one mission file to the next..
First make a back up of the mission file you want to copy from, so you can revert back after editing.. Now open the mission file with tribal IDE or some editor that counts the lines of code.
Mark the number down on a notepad, like 1235 or some thing that line at the bottom ends at..
Now run the game and load the map, highlight and copy a bunch the objects in the editor like some big bridge or a bunch of structures in one area,
Now move to an area out of the area you copyed from, and click past, they will all be recreated there..
Remove any spawnpoints you may have coped with them, click save the mission, exit the game, go back to the mission file, copy all the data below the line you marked down on the notepad, make sure you are below the last datablock before the line number.
Make a copy of your mission file first, in case you need it to start over later. Now copy all the new structure data to your new map mission file just below some structure data in you mission file, like the kind below, watch your code brackets, if you get a syntax err recheck where you added, make sure there are no double };
Save the changes to the mission file, exit, load the game up, if it loads your now ready to keep editing, in the editor.. This is tricky, but it works for me all the time, good luck...
Code:
new InteriorInstance() {
canSaveDynamicFields = "1";
Enabled = "1";
Position = "611.893 1072.4 273.663";
rotation = "0 0 1 77.9221";
scale = "1 1 1";
doDistanceFade = "0";
startFadeDistance = "10";
endFadeDistance = "500";
teamIndex = "-1";
interiorFile = "legions/data/interiors/bridges/rebar.dif";
showTerrainInside = "0";
};