Applying directly the morphing tool in poser without exporting anything is a good start point, though in posed body parts this tool (in particuliar in smoothing) seems to have a curious behavior. The tool works much better when applied in a separate prop (exported body part).

Anyway, for smoothing contiguous body parts (for example hip + rthigh) you have to export a welded geometry of your posed figure, and the same problem will arise when importing back the modified body parts (plus the vertices mixing, fortunately resolvable with a free tool like morpher)