Business Scenario for SD

Hi all,

Scenario:

Customer orders 100 qty of material X on 25th Jan. Invoice is generated on 1st Jan.Terms of payment is 30 days, So Payment due date is 1st Feb.

Now customer doesn't pay on 1 Feb, But he returns 50 qty of Material X as defective on 3rd Feb. We have to return him fresh goods ad the customers pays the invoice

What are the documents that will get created. Please mention the relation between these documents (May be in document flow)

Thanks,

Dattatreya N R