When products have variations, managing inventory means managing the quantity of variations, and the quantity of the parent product should not be manageable (and the product should never be purchasable).
I see some problems on Sellacious about this:
1) In Inventory manager I still manage the stock of parent product and I can't manage the stock of variation
2) In Product management, in the Inventory tab I still manage the stock of parent product
3) I was unable to set up any configuration to allow a seller to change the stock of their variant offers without being able to change the basic characteristics of the variants (Product Title Suffix, Variant Alias, images, attributes, etc..), when more seller offers the same product managed by admin
This bug doesn't allow me to propose Sellacious to a new potential customer where multiple sellers offer the same shoes.