reference document for consignement

Hi guys,

I need to develop consignment sales process for multiple customers. Am confused regarding the four process like consignment fill up,

consignment issue, consignment returns, consignment pick up, do we need to take reference of consignment fill up document number while creating consignment issue .not required then how can we able to track the stock. Of particular customer and order.in case of returns is it mandatory for taking reference of consignment issue.