WooCommerce Merge Orders Extension GPL Overview:

The Merge Orders extension allows you to combine multiple customer orders so you can process and ship them as one.

Why merge orders?

The most common scenario for needing to merge orders is when you receive multiple orders for the same customer. Merging and shipping them as one package provides multiple benefits, including:

• Reducing costs on shipping and packaging—better for you, and better for the planet!
• Streamlining order processing and putting the tracking in one place.
• Improving customer experience—they only have to track one delivery, and they receive everything they ordered at the same time.