For a Item fulfilment upon changing the ship status from Picked to (Packed or shipped ) Netsuite is automatically adding Package value to the package sublist. It is a standard functionality.
The package weight value is from Item Record > Purchasing/Inventory (Sales/Pricing in some forms) > Item Weight multiplied by the Quantity on Item Fulfilment for all items.
Below Attached screenshot of item fulfilment with status “Picked” and there is no package weight
Below Attached screenshot of item fulfilment with status changed from ‘Picked” to”Packed“. After changed the status from picked to packed package weight is automatically set by Netsuite.
