ok this is going to take a while to explain.
You have what seven layers in the editor right? I bet you are only building on like say two of them, and your not using the whole layer grid. am I correct in this assumption?
Let's see if I can explain this properly.
1) When you enter the editor hit the "-" botton until you are on
the first layer. Next build a level using say a quarter of the
grid space on the first layer but two layers high.
2) next move up to the third layer and build a level on lie an 1/8
of that level and extend it down to the second layer and cover
a quarter of that level (make sure you build it on the oposite
end of the layer grid as the first level.
3) build another level on say layer five (make this a small
outdoor level) do not build up or down.
* you now have three levels on one map *
Now you would need to figure a way to set a condition victory or rather. if condition victory attained teleport users to level 2 script. I think you may have to edit something in the source (I'm not a coder, though I do start my school for software engineering in about a week). I don't know if you can use teleporters in MM but that would be another way to set it up.
RF