We are distributors dealing with wholesalers. We regularly have to takes returns for damaged goods or slow moving items. We do not have a particular invoice against which to process a return. 

upon studying this issue, we found that by entering a negative quantity while creating a sales order, the inventory creates a delivery order receipt( return) and the sales order allow to create credit note directly. 

I would like to confirm, if this is the standard process for sales returns but cant find much information. 

Also, we can only create credit notes from sales order if the invoicing is set on ordered quantity but we would like to work on delivered quantity. 

 Also our products are storable and we work on Average costing / Automated and so the returns process should square off interim delivered / Received accounts.