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Update! After doing more research I believe the heads are treated as attachments like the weapons in the character's hands and are not weighted with the bodies at all. Tested this on several, but not all of the heads, and each's neck is detached too. The only resolution I can see based upon my assumption is each of the heads need to be reweighted and animated using the rigs for each profile. This isn't an engine bug so I'm sure TGC are happy about this and more of a animator error. Don't know how much TGC paid for these assess, but these and many more fundamental errors, I hope it wasn't much. Marking as resolved since it's unfixable without major reworking heads and animations.