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If you load a female character with textures, select the face with the material tool, then go to shader you can browse to texture folder. The face will probably part of body texture, but open it and have a look at how the face and body texture is stretched to conform to the model properly. There has to be a tool for this. Cant see doing it manually. You would have to do this.
As for the mesh Daz has deform tools so you can do your own character mods but I have never used them.
Suggest checking Daz forum and youtube.