we are distribution company and are constantly pushing stock to the retailers. Are issue is that 

1) We receive plenty of sales returns of multiple items at a time  from a partner and these returns aren't against any particular invoice and therefore we cant reconcile them invoice to invoice. But i cant figure out how to process a stock receipt and a sales returns voucher without a corresponding sales invoice. 

2) goods that we receive back may contain stockable products / Dented for scrap / Display PC / Etc. Is it possible to assign locations on a linewise basis.