Stuff I'm sure deletes groups; Using the "loop" selection tool. Deleting any polygons that are part of a named polygon group. Stuff I'm not so sure about: Using "triangulate n-gons," "de-triangulate," or any of the other similar menu options. Collapsing subdivisions does not harm groups, nor does triangulating an individual polygon seem to. (Oh...the triangulate command will trash a UVmap 100 percent of the time...) I'm not sure at what stage you are losing the grouping. When I've been trying to track down problems I have gotten into habit of opening the .obj files in a text editor and searching for "g" lines. That reveals pretty quickly if the groups are still there -- and if I got the wrong options to give them the correct names. (In exporting from Poser, several options will create strange group names like "figure1_lThigh:2" instead of "lThigh.") I group the vast majority of my models within Carrara, and I frequently open them in the freeware version of UV Mapper to fix parts of the mapping Carrara does badly.