This isn't exactly a wholesome project. It would be for a transformative game where the character would be able to gain new parts, possibly even change sexes, and the like. However the example: Female character's breast size could increase, or decrease. Or perhaps they disappear altogether.
Then I would go a completely different route than suggested in my first answer:
Look for a so-called "equip manager" script on the master script list - there are three or four different ones available, for example from Yanfly or two variants (old and new) from Tsukihime.
Then define additional equipment slots like "left arm", "left leg", "Torso" or whatever you want.
And your exchangable parts will be implemented as armors set to those bodyparts, allowing you to define a lot of different parts by database work alone.
This is possible with or without additional sprites or face/busts, depending on whether you want changes in the part be visible ingame or not - there is also a script that automatically changes the sprite based on equipment, but that should only be used if you have a lot of different grafics available.