Map tranfers (Like the FT orc Campaign)

Even though I do know alot about triggering, I have no idea where to start on the map transfering. If I send someone some maps could they then link them together for me? Or if possible, show me a tutorial about transfering?

For those of you who don't understand, How to go from one map to another then back to the original map and have all you've explored STILL explored. And you still have all your quests and stuff like that.

most of it is saving to caches and all but i myself am stumped on linking maps togeather