Credit the amount with vendor account without return delivery of material (goes into scrap)

Hi Expert

1) Procure the 10 qty with 1000 Rs cost 10 x 1000 = 10000 Rs (Raise the PO)

2) GR 10 qty and IR the 10 X 1000 = 10000

3) After done the invoice, come to now 4 qty is damaged.

          a) 4 qty make into scrap with permission of vendor ( Not return delivery to vendor)

          b) and the 4 qty value need to detect from the amount which settled the vendor

                  amount 4 X 100 =  -4000

          c) After cleared all, in PO should not be any ope value and qty, if so how to solve and provide solution.

     Regards

     Karan