Hi Michael,
maybe a GROUPING-Function would help - like it exist in CINEMA 4d - to put several objects into one NULL-Object?

The problem in my scene is solved so far - only the export to .obj is actual the problem. (Some objects are not exported into an .obj-File)

Are there any restrictions about "SAVE AS - WAVEFRONT (.OBJ)"?

Greets from Germany
Moritz