Shipjoin is a Shopify app for when a customer places another order to the same address before the first one ships. It finds those open orders, puts the newer ones on hold so they don't ship separately by mistake, and gives you one packing list with total items and weight. Fulfill the first order as usual and Shipjoin copies its tracking number to the others. It never merges, edits or cancels orders, so sales, taxes, inventory and reports stay accurate. Free plan: 20 groups a month.