As per Amazon's policy, you can update (add or remove) 5% or 6 units of an item from a shipment or you can remove the item completely if the SKU units are less than 6.
You will need to pack all the items first and confirm the transportation option. It will then provide you the option to adjust the qty of the SKU in the shipment in the "Confirm Shipping" or "Confirm Transportation" Step.
Follow the steps below to update the SKU Quantity from a shipment plan in the New Prep & Ship.
Pack first workflow (Provide box contents up-front (SPD and LTL)
Pack all the item (including the damaged, missing etc) in Step 2 : Pack and Generate placement options.
Generate the Transportation Option and Confirm Shipping in "Step 3: Confirm Shipping"
Once it takes you to the next Step i.e. Step 4, go back to "Step 3: Confirm Shipping" and Click "Adjust Quantities" Button fir respective shipment you want to adjust.
Clicking the "Adjust Quantities" button will take you to "Step 2: Adjust Quantities", where you can update the SKU quantities within the permissible limit of 5% or 6 units and Click "Update" button.
Clicking "Update" button should update the Qty and will take to Step 4.
You can validate the updated qty.
Pack Later Workflow (Provide box contents after generating shipments (LTL only)
Pack all the item (including the damaged, missing etc) in Step 3 : Pack and Generate placement options.
Generate Tranportation option in Step 4
Confirm shipping in Step 4.
Once the shipping is confirmed , go back to Step 4: Confirm Transportation and click Adjust Quantities for the shipment you want to adjust the SKU quantity.
When you click the Adjust Quantities , it will take back to Step 3: Adjust Quantities, where you can update the SKU Quantities in the boxes as per Amazon 5% or 6 units policy.
Clicking "Update" button should update the Qty and will take to Step 4.
You can validate the updated qty.
Please Note: Once you confirm the shipping the first time, you have 60 mins to update/cancel the plan for a LTL Shipment plan and 24 hours to update/cancel the SPD shipment plan. Post this time, you cannot cancel the shipment plan.