Linked Orders is a WooCommerce extension for marking newer orders as being logically connected to older ones.
What that means depends on your use-case. For example, an order containing a warranty extension should probably be linked to the order containing the product that the extension is for. Or an express processing fee paid separately. Or anything else that you’d like to keep track of without having to open up all the customer’s orders to figure it out.
Empty linked orders can be created using the admin interfaces (e.g., for email or phone orders), or you can link orders programmatically to fit your existing workflow.