From my experimenting, mostly Hex to Poser issues of how to maintain a sharp edge I found splitting the vertices in UVMapper apparently creates a new mesh by altering the edges by the given crease angle. that's why I map after I split.
to prove this to myself I made a very simple wall. Went through the splitting process.
Made a sizing morph and when I tried applying it to the wall in Poser I got a wrong vertice error.
Split the morph obj then it worked. It matched the vertice count of the wall.
  I haven't seen an Un-Weld function in UVMapper so I can't comment on how that might work.

This technique can be further refined, depending on if the modelling app can assign textures and export them. Then the areas that need to remain sharp can be split by material.

Is this the proper way to fix a bad obj? Who knows but so far between splitting vertices and checking for concave facets I've been able to fix most anything I've needed so far for use in either P4pp or P7.

I must remember to remember what it was I had to remember.