Hi all,
I found an interesting acticle on geometrically (more) correctly combining normal maps and implemented the Whiteout method in a node group for Blender 2.80, with additional strength slider for each map.
In case it’s useful for anybody, here’s a blend file with the node group and a usage example. For import to your projects append the NormalMapBlend node tree from the blend file.
normal-blend-whiteout.blend (349.0 KB)