I want certain items not to ship separate from their pre-ordersUpdated 2 days ago

To mark a product as a add-on item (and not ship separately from a pre-order cart), go to its product page in Shopify and add the tag pd-add-on-item.

Adding this tag prevents the item from being treated as an individual in-stock product and exported into Shopify right when the order is created. 

Note: This functionality only applies to brands using our combined checkout, which allows in-stock and pre-order items to be purchased together.