The way I’ve been doing this is as follows:
- Make the UV map in Lightwave.
- Save out an obj of just the surfaces using that UV map.
- pull that temp ‘object’ into Zbrush.
- Paint as desired
- save out the texture; the temp object is unimportant.
- apply the texture map to the original object (to appropriate surfaces) in LW.
I find this a handy work-around to several issues. It seems that ZBrush doesn’t handle multiple UV maps on imported objects well at all, it seems to layer them on top of each other and then you get the red overlapping areas. So to get just one UV map into ZB to paint on, you have to simplify and pull in just those surfaces that apply that one UV map. Loading in the whole object and trying to select the surfaces to paint on just doesn’t work (for me at least).
Another perk of this method is, if you want to use an auto UV map from ZB for just part of your object, you can save out the object from ZB, cut and paste that part into your LW object (remembering to delete the corresponding parts of the LW object first, of course). Then you will have the ZB UVs on the part you pasted in. I’ve used this a couple times in special situations and it was really useful.
Not sure if this applies directly to your concerns, but may be useful. I find that trying to be really flexible in my thinking about how to approach LW-ZB puzzles helps a lot, every situation seems to require a slightly different approach. Hopefully there will be better communication between the two programs in the future.
Oh, and what you name as PARTS in Lightwave seem to be the only things that show up as GROUPS in Zbrush.
hope this is somewhat helpful,
NJ