Hi Mohammad,
Well I don`t think collada (.dae) will be suitable because it`s a very large scene (huge);
I also tested the plug-in (LumenRT plug-in to CityEngine) but, indeed, it`s not working properly... neither exporting the scene as pieces of .obj`s will work because I don`t want to import separately the pieces ...
I`m thinking of having 2 versions of CityEngine installed on the machine until something will work with 2016.x verisons...:)
Ionut