Further to this, you will notice that on animation of the bottom drawer, all move. To correct this the animation must be moved to inside the copy. Hence another level is created.
My reason to ask about your interest in DCs is to guide you in your development. Although internal copies has its merit it also has many drawbacks, in that it greatly increases file size and becomes more complicated in structure, as are becoming aware. So if this is a basic project then okay, but if its a development toward a kitchen design system with quantity lists, materials... then I suggest looking at
https://sketchucation.com/plugin/1613-gkware_cabmaker
If you still wish to pursue your own, then I can help, but the DCs need to be simple and have the ability to swap, plus incorporate some simple ruby scripts to make it easier to handle.