Blend Normal maps? GPU

[DanSHP]

I have one material with x1 normal map, I then use a Bump Material to add another normal map on top. If I add another Bump Material with a third normal map, it doesn't work.

What is the best approach for using multiple normal maps in a material/s?

Also, would it be an idea to have the Bump Material UI look like Blend Material? So we could have a list like structure, instead of having multiple bump material nodes one after another in the node graph?

[fixeighted]

You could try the method used here, using an OSL blender that seems to be able to be made to support 3, though he does say he doesn't recommend it (I think; it's in Spanish and I'm far from fluent).
Appears to work just fine though
https://www.youtube.com/watch?v=XwRgO4osx0o&t=412s

[fixeighted]

Indeed that seems to work ok even without the osl in this simple test.
In fact it works much better using gpu than cpu, which is a far fainter result.