Subdividing presumably means that you are adding polygons, which is a no-no. You can resculp the mesh, but you have to make sure that vertex count and order stay the same.

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So everything seems to work really well when exporting from CC4 to blender.  When I go to import the character back into CC4 I keep getting an error code.  It doesn't seem to matter if I use the plug in, or if I just try to use import it as a regular FBX file.  Any ideas why I'm getting this issue?  I've tried updating the blender add on and the files for the plug in.  Again though, it doesn't seem to be working even without those.  All I did was transfer over a Caleb, I subdivided his torso, and gave him a growth on his belly to try to see if I could get this working.  I've been at this for hours so any help would be greatly appreciated.