Thanks for the additional info.  - Something you might try... select the head part of the frozen version of the figure, do a cut/paste to seperate it from the other body parts. (you could do this with all the body parts actually) - With the morphs in the "base" mode, export all the body parts as one .obj file (even though they are seperate objects now) Poser will load it as one object and weld the parts in the Setup Room.
Then export your head morphs as individual obj's. I have found this works for me. For some reason, Poser reacts differently when it recognizes the points where the head and neck seperate as a border edge rather than points in a continuous mesh, even though the points are occupying the exact same space.
Good luck with it!

Hey! His nose is dry! ... Someone should lick it,  just in case. - Diego