I'm fairly sure that UVMapper (either version) will do what you want.

Load the grouped OBJ, then export the UVs (this saves the grouping as well).
You should then be able to load each ugrouped OBJ and used the UVS file you just saved to set the grouping to match the original grouped OBJ.
(This is the basic recipe for creating FBM with a modeller that treats groups as separate meshes)

There are scripts that will then take the grouped morph OBJs and apply them to the figure in Poser.
svdl did a free one (see Python forum), PhilC has something for this stage in his Poser Toolbox, and I think Netherworks also has something available.