As pjz99 said the breasts of V4 are just linked magnets tied to a parameter dial, so no geometry is involved here so the breasts not working any more is just that the ERC links had been broken or the IK chain had to be updated to accommodate the new parts. Easy to fix.

I tell you this because the first incarnation of NBS for V4 was something along the lines of what kawecki did. One of the downside of it is when you add new groups the vertex order change so none of the morphs of V4 works anymore in the chest area. So you will lose DAZ body morphs or my NGM morphs which is a tragedy! ;D

This means of course that all the body morphs or muscular morphs had to be incorporated to the new chest figure to regain body morphs and believe me there is no automatic process for this you have to redo them by hand ant they are a lot!

I have tried other ideas also but eventually I returned to the geometry morphs for NBS because right now is the only way to obtain precise bends or folds in the figure breasts. Maybe if Poser had vertex maps a nice rig could be developed for breast movements but right now we have only joint parameters. And they are not enough for this.

NBS for V4 is now in its final stage, has taken a little more than I had wanted for various reasons but I can tell you is very close now.