There is an -utopic? -solution , maybe someone has already done it ? taking V3's head and joint it to v4's body . I saw some threads on putting one character's head on another . The dream would be to use V3's head morphs and v4's bodymorphs and textures ...

Or - maybe - subdivide the head , create a new V4 obj file , and do the same for all needed head morphs :
a head morph dialed on 1 - export - subdivide at the same level-  import as a morph target for the new head and so on ...
Personal use only and not compatible with character packs -unlesss doing the same for a custom head morph ! , but easily compatible with textures .

Alice's and GND4's Tailor !
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