Hi Gordon,
If you want to modify V4 in Carrara you'll need to first select her geometry.
Basically, open up Victoria 4.2 in Carrara, then expand the hierarchy in the instances tab. (Lower right hand corner; click the triangle next to "Victoria 4.2")
Highlight the word "model" on the list, then switch over to Carrara's vertex modeler. (Click the wrench icon on the top right of your screen)
Once you're in the vertex modeler you can sculpt V4 to your liking; just don't add or remove any vertices as this will mess up the rigging.
When you're finished, switch back to the assembly room and you'll see the changes you made reflected in the figure.
If you want to try this with Hexagon, then it's a completely different animal-usually referred to as an External Morph Target. I know how to do this with Poser, but not Daz Studio :(
JT