Separate credit memo qty & Return qty (billed) on SIS report

Dear Gurus,

I check SIS report and see that both billing from Credit memo request and billing from Return order also update field Return quantity.

This will lead a problem that I can separate actual return quantity (Billing from Outbound delivery already PGR) and credit memo quantity (billing from SO credit memo request.

I really need to know how many return good billed, so check actually quantity sold.

Can you give me an solution for separate credit memo qty & Return qty!

Thanks

Manh Tuan