This article explains how to change drop ship POs and Sales Order for related drop shipments.
How to change Drop Ship Purchase Orders
If a Vendor makes a change to the Drop Ship Purchase Order, you can modify the quantity or cost of the Drop Ship PO by selecting to edit the Purchase Order, provided the Drop Ship PO is open at that time and the line is currently scheduled and hasn't been invoiced. This will NOT impact the related Sales Order so if you need to make a change to the quantity, we recommend you make this change on the Sales Order and not the Purchase Order.
How to change Sales Order for related Drop Shipment
If a Customer would like to make a change to an open Drop Ship PO, you should be able to edit the Sales Order Drop Ship line and make the necessary change to the Quantity or Price. If you do need to make a change to the quantity of the Drop Ship line on the Sales Order, you will be prompted with a message asking you if you want to update the quantity on the Purchase Order. Selecting 'Yes' would update the quantity of the open Purchase Order. You will need to refresh the Purchase Order to review the changes. If you select 'Cancel' on this message, you can add a new line to the Sales Order, in order to create a new Drop Ship PO for the changes.