Missing feature

This is a great plugin, but from my point of view something is missing.
I’ll try to explain myself.

I have 1 product that use a black backpack as a base with two variants.
One is customized with text “GOOD” and the other with the text “BAD”.

in the attribute stock I created the attribute “backpack color” with “black” as a term and stock of 10.

Now, in this example I already have in inventory 2 backpacks with the text “GOOD” and zero with text “BAD” and of course the 10 black backpacks without any text.

I manage the stock at variant level inserting 2 for “GOOD” and 0 for “BAD”.

What I expect is that the stock decrease first at variation level (the backpacks already customized) and than, when this stock reach 0, from the stock at attribute level (the backpacks to be customized).

If I sell 1 backpack with “GOOD” text, the actual behavior is to drop 1 from the variant stock and also 1 from the attribute stock.

There is a way to do this or do you need to change the code?