If you sell bundles in your Shopify store and also sell on Etsy, the stock of each item inside a bundle needs to stay right in both shops. Shuttle handles this differently depending on where the bundle sells, and the Sync stock for bundle components setting controls what happens after an Etsy sale.

Shuttle treats a Shopify product as a bundle when Shopify keeps a list of the items, or components, inside it. If a bundle app builds bundles without that list, Shuttle sees an ordinary product.

When an Etsy listing matched to a Shopify bundle sells, Shuttle can lower the stock of each component in Shopify. Shopify does not allow stock changes on the bundle itself, so Shuttle updates the components instead. This only happens when Sync stock for bundle components is turned on, and it is off by default.

For each bundle sold, Shuttle lowers each component by the number of that item the bundle contains. Sometimes the buyer picks how many of a component they get through an option. Shuttle cannot tell which amount the buyer chose, so it lowers that component by the smallest amount on offer.

If a component is also matched to an Etsy listing, Shuttle updates that Etsy listing with the component's new stock too. If a component has no matching Etsy listing, its Shopify stock still goes down, but Shuttle shows that it found no matching Etsy listing. See Matching Etsy Product Not Found to match it.

Shuttle changes component stock only for Etsy orders. If you change a bundle listing's quantity by hand on Etsy, its components in Shopify stay as they are. If an Etsy order for the bundle is canceled, Shuttle adds the components' stock back.

Shuttle updates bundle components only when everything in this list is true:

To sync stock, you need the Growth plan or higher.

Shuttle never splits a Shopify bundle sale into its components. When a bundle sells in Shopify, Shuttle only updates the Etsy listing matched to the bundle product.

A component's Etsy listing changes only if Shopify lowers that component's stock and the component is matched to an Etsy listing. Shuttle picks up the new stock when the component's product changes in Shopify. Shuttle also runs a regular stock check that catches drops it missed, but that check only copies decreases to Etsy, not increases.

If you want Shuttle to update a bundle and its items whichever shop the sale happens in, set the bundle up as a kit. With a kit, Shuttle knows which items make up the bundle. A sale of the kit lowers its items, and a change to an item updates the kit's stock, in Shopify and on Etsy. You set kits up on the Kits & Bundles page.

To use Kits, you need the Growth plan or higher.

See Using Kits & Bundles.