Bukkit

+Basically, I have created a Flat world for a City RP server with a friend. I'm wanting to build underground for Subway stations, but the flat world is only a 4 block layer, including the bedrock. I'm wanting to have more layers so I can make a subway station and things underground, so I need to know how to import that "city" world into another world with more layers. How could I do that?

+I really don't wanna have to copy and paste it all like 30 blocks higher and then world edit a ton of blocks under the city. Then I would have to place all the doors because doors don't paste right in world edit.

+So if you could please tell me how I would go about uploading that city into a new flat world with like 30 layers or so.

*All the stuff under here doesn't really matter*

What steps will reproduce the problem?
1. N/A

What is the expected output? What do you see instead?
- N/A

What version of the product are you using?
-  5.2.6 (The latest one to date)

What version of the craftbukkit/bukkit are you using?
- I'm using Spigot actually. The host I'm using doesn't allow me to see what version of Spigot, but I'm pretty sure it's the latest or one of the latest for 1.8.8 I believe.

Do you have an error log of what happened?
- No

Please provide the result of /mw debug below: