Well, here's the tutorial: https://www.youtube.com/watch?v=wsO1eozb1Qk

My previous computer was from 2014 and couldn't run recent versions of Blender. Then again, it was running Linux, which tends to aggravate driver issues. Myself, I haven't used Blender in ages before getting that new computer two years ago, so I have no idea which version one would need.

At any rate, the method relies on two things: one, Blender can "bake" a node-based texture into an image map, and two, it can use different UVs in different nodes of the same shader, so it can use on set of UVs to generate a texture and another one to bake it to.

The part that's missing from the tutorial is how to load to different UVs from files and apply them to the same geometry (in the tutorial, one is generated from scratch right within Blender). In theory, that should be easy and obvious, but with Blender, things rarely are.

-- I'm not mad at you, just Westphalian.