I have a different apprpach. I don't encode anything, don't decode, use nothing for the ket, no original data is included in the updater and you even don't need to hace the orifinal figure.
I obly add the information of these two new body parts to any existent character.
As I found a way to add new body parts without the need of modifying the geometry I only change the cr2.
Of course, if you don't own Vicky4 oe any Vicky4 comoatible or conforming character and apply the updater you will not have Vicky4 with nipples, you will have some other figure with nipples and unless this figure has a similar geometric shape the result will not be good.

Stupidity also evolves!