Question about Generators and Normal map

Hello

I write my first post today about a question regarding generators and normal map. I hope to be at the right place for that, I'm a bit lost between the change of forums in with all these new accounts. Here is my situation:

I have to do 2D game textures for somebody. To save time and have flexibility, I made them with Substance Painter. I simply created a single plane as texture "support", then imported it to starting creating the textures. I've made them using diffuse, roughness and normal maps, but I would like to add dust for example, that would be on the top of my "geometry" and in the cavities. In other word, I would like to have the generators using the current normal map instead of the generated one at the initial baking textures.

You would tell me that I simply have to do the high poly versions in 3DS Max then bake it into Substance Painter as intended, but I have to do several ones on the same template/style and it would be much easier and faster do to all in SP.

Based on some searchs I already did too unclear, I heard that this is not officially supported for now, but workarounds exists. So this why I come today on official forums, to get, I hope, the advices and tips from experienced artists.

Thank you!