Reducing inventory by specific amount at variation level.

I am hoping to find a way to apply specific inventory reduction amounts to product variations.

We offer discounts on products at different order volume levels and these are set up through variations. For instance, 1 unit = $10, 2 units = $18, 4 Units = $30. The issue is that handling inventory through this does not reduce the inventory by the correct amount.

I understand that this pricing structure is normally handled through bundles however we prefer to use the variations method and would like to be able to apply a specific inventory reduction number to the variations. Is there a solution that I am missing or a plugin that will do this? I can’t seem to find any information on reducing inventory by 2 or more for a variation.

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