That’s the second time I read this isn’t possible. However, I was able to edit, save and test an existing map under a new name, without copying everything.
It’s a few weeks since I’ve done it, but it was probably something like this for battlegrounds:
I opened the “AOCTO-Battlegrounds_P” (D:\Program Files (x86)\Steam\steamapps\common\chivalrymedievalwarfare\UDKGame\CookedPC\AOC\Levels\Battlegrounds), edited it and saved it to “D:\Program Files (x86)\Steam\steamapps\common\chivalrymedievalwarfare\UDKGame\ContentSDK\Battlegrounds” as: “AOCTO-Battlegrounds_edit_P”. The UDK asked me if it shall edit all the existing references to the name to the new one. I pressed yes and copied all the other files in the same folder as:
I can, without any problems, edit it, save it and test it. Haven’t tested yet if I can cook it without problems. But I think I should.
Have I missed something though? I’m new to the UDK, so possibly that’s the case.