Change material cost in Sales return process during PGR

[mfbaig]

Hi all,

I have an urgent query - during sales return delivery and PGR (Post goods receipt) below mentioned entry is posted:

Inventory Dr.

COGS Cr. 

My client requirement is to change this amount - COGS amount as per decided value. This can vary for each material.

Any standard solution / customized solution using ABAP will be accepted. Please guide in this regard. 

Just to reiterate it is quite urgent. 

Thanks.