Can levels overlap?

We’d like to separate our maps and have the terrain in one file, and all the other actors and scripting in another file. Fundamentally, we need something like UE4’s “layers,” but we’re using exclusive file checkouts in Perforce, so we can’t use the layers system in UE4 for this since that keeps it in the same file. We’d like the artists to be able to work in the terrain in one file while the designers do scripting and actor setup in another.

This is probably a stupid question, but is it possible to just have them in separate levels, and then load both simultaneously? One of us is of the opinion that levels have to be in different places, and reading the documentation for the World Composition User Guide World Composition in Unreal Engine | Unreal Engine Documentation didn’t clarify the issue as we’d hoped.

You can use Levels browser as a “layers” tool.
https://forums.unrealengine.com/showthread.php?22909-Team-working-how-to-collaborate-on-the-same-scene

One caveat is: foliage can not be moved to a separate level, as it has hard link to the geometry it painted on.
Shouldn’t be any issues with having an overlapping levels.