Generally the character would need to be in the default position when you export if not the position you exported your character out in will be part of the new morph. 

If the new morphs are extreme like you mentioned and re-rigging or possibly new UV mapping needs to be done then you can't release the character. If you were to release a re-rigged version or a new UV mapped version , it actually becomes a new model and the buyers of the character would have to have that model.  Then that also means you can't sell the re-rigged or new uv-mapped version without contacting Daz first because they own those models. The only thing we are allowed to share or sell are textures created for V4 or M4, poses, and morphs we create.

However, if this is for your own personal use and you don't plan to redistribute anything than you can re-rig or change the UV-map to better handle the extreme morphs.

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