B4 and after
basically you use [ g] max to edit the vert locations of any part you want in the Editable mesh level of the stack Just as Taina's read me says. NO operations , no cutting no attaching no welding no collapsing , the better you are, the better it will be, you also can edit uv cord and replace them as well a very handy tool
the lips are only fuller in the profile shot you can see the difference anyways you get the idea
here is the link to the tool for those that want to see what they can do
Follow the read me to a T, don’t rename any model sections in max and unlike chuck’s replacer this is a 6 part deal and very unforgiving one mistake and the app generates an error or crashes.
A good understanding of 3d modeling is good to have but don’t be intimidated by XYZ