Graphics load / unload multiple scenes with dynamic GI ?!?

Hi,
it seems Unity 5.2.b5 should able to load scenes additive with baked dynamic gi lighting?!
I could manage to load a baked level (dynamic gi) with loadleveladditive, but after removing it (destroy game object) and loading it again, the prebaked dynamic gi has gone?!
What is the best way to load / unload levels with prebaked dynamic gi? This is a very essential issue!!

What I do now is:
- ManagerScene which loads additive / unloads (destroy) scenes
- 3 level scenes with dynamic gi, reflection probes (realtime), light probes
- only 1 of those 3 levels is present at the same time
- the levels are used (loaded/unloaded) more than 1 time

I hope someone can help me out here. Maybe you have some hints / better ideas how to load / unload levels with dynamic gi?? Thanks in advance