These are only workarounds for an very old issue/feature VaM inherited from DAZ3d. In DAZ you have head morphs (face, brow, mouth, nose...), body morphs (legs, arms, chest...) and full body morphs (mainly full "looks") strictly separated in categories. Deep in the back of my mind I think I know there is a 3d party tool to split those full morphs, but I never have used it.
Workaround: dial-in the full body morph, use the morph merger plugin and choose the option to split in head/body.
Though, this is not very elegant, I know.