Hey guys, with my current store, I sell a main product and then a separate product that is an add-on to the first product. A customer would purchase product A (paid shipping), creating an order, then comes back 5 minutes later and purchase product B (no shipping because it is an add on). Now because product A hasn’t been fulfilled, it is ideal for the second order to automatically be merged into the first order and shipped together via the chosen shipping method. Currently, our backend is having a hard time finding and combining these orders because the shipping method is labeled differently.
No, we cannot ship them individually as they are too cheap.
Yes, we already have bundles and upsells however this is for customers that return from email marketing or retargeting.
I want to ask whats the most efficient way to do this or is there an app for something like this? Thanks
Hi @jasonzeyu ;
We’ve developed the Shopify app “Mergify” as a merger of orders, so the problem of merging orders can be solved easily. With Mergify, you can effortlessly combine multiple orders into a single order, all without the need to restock any items. Your inventory remains unchanged! By creating a combined order that includes all the necessary items for fulfillment, you can conveniently ship all the orders together to the customer at just once.
One of the remarkable features of Mergify is its ability to automatically identify orders with the same customer and shipping address, seamlessly merging them without any manual intervention. This automated process ensures that you can optimize your shipping operations and minimize costs. A growing number of stores are already benefiting from Mergify, enjoying significant savings on shipping costs.
We invite you to experience the convenience and cost-effectiveness of Mergify for yourself. If you have questions, our team is readily available to assist you.
Mergify | https://apps.shopify.com/bestapper-mergify
Merge & combine orders to save on shipping costs
You can do this manually while both orders are unfulfilled:
- Create an extra order (in test mode with test payment gateway)
- Add product A and the add-on from both orders
- Mark it as paid & add the customer
Then fulfill, cancel, or archive the two originals. I would simply archive & fulfill.
Test it out with one example first to see how your fulfillment flow behaves. Also check if your inventory is updated as you want it to be 
With this way your sales & tax should stay intact.
Disclaimer: I’ve built an app for that 
Since you asked for automatic merging: that is exactly why we built MergeIt (full disclosure: it is my app). It detects follow-up orders from the same customer and merges them automatically, with settings that protect your sales, tax, and inventory numbers 