Never tried it that way but from my experiments it could work. I think you should be able to add all the none constrained verttex in the default group in a pp2 file. It should overwrite the groups so no need to add a pose with it. If you do so the bad boys can also use it if they want to have nude shoulders and more. I would do two files one no constrained and one constrained so that the user can switch back to the default values and in this case the vertex needs to go in the constrained.