FLAW: Unable to assign serial numbers to Sales orders in Zoho Inventory

FLAW: Unable to assign serial numbers to Sales orders in Zoho Inventory

We use sales orders. Staff pick items and assign serial numbers to each line-item.

With zInventory you can't add serial numbers to a Sales order. 

How can an inventory system not have such a basic feature? 

Serials can be added when the invoice is done... but how is accounts dept supposed to know the serial? The most efficient way to assign the serial is when the item is being picked / packed.