How do I blend billboards with 3d fog?

Howdy, been working on a maze horror game and I'm having an issue where the empty space in billboard sprites are cutting through the fog effect, resulting in an ugly box surrounding the sprites. How do I fix this? I have the billboards on their own layer with camera distance sorting, the fog effect is on the layout as a whole.

Thanks!

I'm hoping it's an easy fix, but I've been trying different things, blend modes, trying the fog effect on different layers, but I can't seem to find the right combo. I've been looking at the foggy zombie shooter example, but I don't see what it's doing differently. Help pls!

1. Remove the fog effect from the layout.

2. Apply the fog effect to the enemy billboard.

3. Put the billboard layer on top of the game layer.

Hello :)

To complete the previous answer :

1. Remove the fog effect from the layer
2. Add the same fog effect on both layers (game and billboard)

It will almost be perfect, but I noticed that if the sprite is in front of the camera, it will remove the fog effect in the transparent areas of the 3D box. Don't know how to fix that yet !

Also I'm glad someone uses the addon I updated with the 3D camera !

1. Remove the fog effect from the layout.

2. Apply the fog effect to the enemy billboard.

3. Put the billboard layer on top of the game layer.

This worked, thanks! It was driving me crazy xD