SKU’s for multiple-category products

Hi there,

We’ve developed a Woocommerce webshop for a clothing company. This webshop is connected to a stock management system with a custom API.

In the stock management system each product variation has a unique SKU. Each product variation is a different product color.

Products appears in collections. Twice a year a new collection will be added to the shop. We’ve used categories for that, so each collection has it’s own category.

Now the difficult part: sometimes a product will be continued a year later. In the stock management system of the client the product will be kept the same SKU as it has in the previous collection.
But the product variations can change. For example, new colors can be added or some colors won’t be continued.

Because in Woocommerce a SKU can only be used once, we edit the product and add it to multiple categories (collections). Now the product is showed on both of the collection pages.

But how can we handle changes in variations (new / removed colors) between collections? Because we’re using the same product, changes in variations will apply to both the old as the new collection.
So we want to have different variations in different categories. We’ve a workaround now, to clone the product, add the new variations, and only show this product on the new category, but then the product appears twice with two kind of variations (of course). So this isn’t the best solutions.

Is there anyone around with some ideas to fix this?