To partially fulfill an order you will need to split the order into separate shipments by following the instructions below.
1) On the Orders tab, click “Create label” next to the order in question.
2) Input the dimensions and weight of the first package in the shipment.
3) For the second package, find that same order on the Orders page, click the drop-down arrow next to the “Print Label” button, and select “Create Another Label" and input the dimensions and weight of the second package of the shipment.
Note: Shopify customers: you must change your Shopify settings within Shippo to stop the full shipment from automatically being marked as fulfilled in Shopify. Go to your Settings tab and scroll down to your Shopify settings. Uncheck both boxes - "Fulfill order on Shopify” and “Send notification to customer via Shopify.” When you uncheck these boxes, the order in question will not show up as fulfilled in your e-commerce platform. Once you finish handling the partially fulfilled order, and you're moving on to process a new order, don't forget to recheck the box in your Settings.