Help! I need explanations about post processing inputs 0-6 on the scene texture node

So I’m trying to create transitions between two post processes similar with this one:

However in this tutorial he’s lerping between postprocessinput0 and scenecolor scene texture nodes, I want to lerp between two post process volumes that already exists inside the level. How do I put another post process volume onto postprocessinput1?


Sorry to bump this without an answer, but I’m looking to do exactly the same thing as well. Any help?