Static navigation with level instances. How to make it work?

I need to pre-build navigation for levels, and then put these levels into a persistant one.
These sublevels are placed randomly, and thats the biggest problem.

I found this post, it works perfectly if levels are pre-placed, since it spawns level’s navigation exacly there, where it was built. However, it does not work in my case, where level instance may be spawned anywhere.

I need to somehow “merge” 2 navigations i guess, to attach the static navigation of Lvl2 to Lvl1.