[Stiglr]

Ah, I see.

I'm not the best person to ask for your *real* question. I *think* it can be done, but I've never done any kind of "auto unwrap". I always create my own texture files from (copies of parts of the) original model, arrange them within the viewports and take a screen grab that's perfectly square (or that fits the power-of-2 size requirements of my target game engine). Then I label and texture the screen grab in a dedicated graphics program (Photoshop). It's slightly more difficult and time consuming, but the payback in terms of control of where parts are arranged on the texture file itself makes up for the "hassle".