When you have an order which is only partially ready to be shipped or contains products on backorder. With the Split Orders plugin, you don’t have to keep the customer waiting — split the delayed items into a new order so that you can ship the products you have available.
When you use different couriers for different parts of order and want to attach tracking information for each shipment. Split the order to match shipments and attach tracking information to each order using Shipment tracking.
When the customer asks you to ship part of an order to a different address. Split those items into a new order, update the shipping address, and process each order separately.