when I try to render separate layers I have no transparent background reason for volumetric scattering. is there a way to solve this?
Could you be a more specific? Attach simplified blend file with issue via https://blend-exchange.giantcowfilms.com/. Add screenshot with highlighted issue and ideally some reference how should it looks like for you fixed? Thank you
Here is something that seems to be working ... not perfect, but hard to say what is your story.