Yes, I feel that I come up close to a solution. You said, "it's a case of non-identical vertices at group boundaries or the lack of proper group locations and welds". I think first answer is close, because, I checked "Show Multigrouped faces" and "Show non-grouped faces" in "Grouping tool". And I checked by "invert group" in "Hidden line Display". There was no lack group location. So, I want to know to making "identical vertices" I think it is made when import obj file. When import obj file, popup window open, and there is "weld identical vertices". Of course, I checked it. And I imported obj file in Poser, and made bone, and made 'Auto Group'. And I commanded "weld group" before close Group and before leaving Setup Room. I just commanded 'weld group" each group - bone_1, bone_2, bone_3, bone_4. And I didn't touch any fix. There was defolt value - 0.000086. Do you know what I did mistake? You can see my image in next website. http://www.visionmode.co.kr/001/born-02/009.html