I can't exactly figure this out, I haven't found anything to tell me how to do this (if it's even a thing). I have a new piece I added onto my mesh with its own texture set. There's another texture set (on another mesh piece obviously) with something I want to clone stamp onto a new layer in my new items texture set.
I've only ever seen people clone stamp onto layers that are in the same texture set.
I hope this is clear enough an explanation, I could try to visually show what I mean if needs be.