Something a little different, and potentially useful for others.
I made this file to help me do some skin textures for the LIE system in DAZ. I went through and "collapsed" all the materials down to the four you see by removing the eyes, teeth and mouth. I then exported it out of Blender and into Painter.
I just noticed that the 2020 version finally allowed painting across tilesets so it's time to try it.