How to change a "blendable" material in a PostProcessVolume in game

I have a global PostProcessVolume in my level. It has a blendable material that basically draws the outline of meshes with the Custom Depth enabled.

The material is an instance material, and I would like to do some things like change the parameter “color” defined inside of it in order to change the color of the outlines when some events are triggered. I just don’t know the best way to do it, since I wouldn’t want to have a reference of the post process volume or its material constantly; I would like to somehow get it when needed, change the parameters I need and discard it.

For example, is there a way to find out the post process volume in which a given component in the world is in?

By your example: you mean checking the overlapping components inside a post process volume?

Didn’t get exactly what is your problem. Would you mind giving more details about how are you currently changing the material’s parameter?

I got the same problem, and can’t find the solution. I’ve posted question here:

I got working solution for UE v.4.17. Here is the youtube video:
Also I can show material scheme if you ask for it.