I broke a large level up into chunks to be streamed in and out by trigger volumes. Persistent level with a Landscape and light source, and 3 other levels with different sections of the level interior.
How to a build the lighting? Streaming the levels in seems to break the baked lighting. Do I bake them all at once or bake the levels individually with individual light sources for each level… scratching my head over this one!
I’ve had some issues with that too. I’m curious to know the proper solution. Also at some point I need to have a building destroyed and replaced with another. I was going to do that with 2 separate maps in the same spot.
No expert has any info on this? 
The only thing I know is that the red warning only goes away if I build everything all at once. I have issues with one of the maps breaking immediately upon restarting the editor with NO changes made. It says 16 objects are unbuilt. Its always 16 too. There are hundreds when I actually break that map’s lighting myself.
I’m also very interested in how I build two maps that are in the same place.