I have a store I have setup with bundles on one product page
Variant 01 - X
VAriant 02 - X + Y
Variant 03 - X + Z
Variant 04 - X + Y + Z
Basically, I want to track inventory for X Y and Z and show out of stock if one of them has 0 stock
If you have bundled up each variant then the inventory should be tracked across all bundles based on component quantity.
Our app will update all lines to the quantity of bundles that can be built. So in your example if X was 0 all the variants would be updated to 0.