Spark Shipping allows users to determine where to send order/partial orders fulfillment requests. This works when you want to Reprocess an order that was previously processed, or when you want to process an order for the first time after it’s been received and put on-hold in Spark Shipping.
To do this, go to the Orders page > search for your order and click on the order ID.
Find the Order Items section of the page, and click on the ‘Edit’ button next to each line item to either exclude that item from being processed or to override the vendor that Spark Shipping already selected based on the SKU Mapping and the order routing logic that’s already in place.
Please note that setting an item to 'Excluded' or 'Canceled' will prevent that item from being processed with the order. Any other status will still process the item when the order is processed.
Make sure to hit Update before you go back and reprocess the order.