Do you want to make the lip color area a bit bigger and blend it into the face a little ?

Your pic seems to be missing a bump map in the lips,  one of the supplied textures should have a bump map that will work.   runtime/textures/daz/characters/bmilwom/v4/v4smplfaceB.jpg from memory. 

 

If you want to extend the lip texture past the lip material zone , you can apply a mask to the face texture.