Hi,
SAP has designed CS process as 1:1 ratio it means that create a service notification for each
quantity and create repair order and PGR and once you get them and try to fix the issue and send them to customer and make an invoice.
For example,out of 10 pcs, If two pcs has been fixed the issue then send that 2 pcs by creating outbound delivery and make an invoice.In this way,we will not have any issue but the issue is little bit difficult to make service notification , repair order and PGR for each and every quantity.
Kindly let me know if you have any doubts on this.
BR's,
Naren