I downloaded the single vtools_multiTilePainting.py add-on. Replayed the silent instruction video a couple of times to see how things were setup and what nodes were being created.
Blender crashed when I tried to add a Multi Painting ‘Layer Set’ to an Image Texture node I had. But once I saw what nodes it added I found I could add an image texture back in one of it’s own Image Texture nodes
yeah this requires a bit of trial and error but it works fine. There are few moments where it crashes like if you are in cycles and texture paint mode and try to go to blender internal. Or when you add image texture node and then you try to go to texture paint mode. This addon does not like image texture nodes that were not added with build in buttons. If you need some external textures you can create group and put those nodes inside.