Blendshapes on Blendshapes

I’m curious to know, if I have a character head with various blendshapes to move eyebrows, mouth, etc - is it possible to then create a blendshape that will change the entire structure of the face… like make the characters head skinnier or fatter, but still retain the ability to move the brows and mouth on top of the new base form?

Has anyone had experience or luck doing something like this? What are some good strategies if it’s possible?

Blendshapes/Shapekeys/Morphtargets blend between each other, that means if you have a blendshape of your character smiling and another of your character opening his/her mouth you can use them both at the time to make your character smile with the mouth open. So if you do another Blendshape of the head of your character growing or shrinking, you can apply it over the other blendshapes you have without almost any problem, the only problem is that they blend aka they don’t overwrite each other, that means that they could deform the mesh in ways you don’t want, and in that case the best is to do another blendshape only for that without mixing the others. Though in Blender (I don’t know if its the same in other programs) you can create a blendshape from a mix of others so that work of making new blendshapes can be easier. Anyway, I hope it solves your problem.