The shapeshifter only swaps the figures heads, but doesn´t change the neck.

And in Unimesh figures the neck is actually part of the  jaw, so if the head is deformed too much, the seam gets completely messed up.

Morph injection won´t help you. either. Once you morph and/or resize the head beyond a certain point, you must create a matching neck morph.

I had this problem a lot with my Unimesh based child characters, and all I could do was to export the neck into a modelling program so I could move the vertices one by one.

Not easy but the only way to get a quality morph without texture stretching around the jawline.

stahlratte