Net value of Credit memo must not increase, but accountingdoc must generate

HI All

This is my sales- return process

Sales order has been created for

Material : Ax001: 10 Qty : Total price : 100$ Per unit = 10$

Sales order has been created : for 10 units (sales doc number:AAAAS)

Billing has been done : 10 units for the value 100$

Accounting documents posted : Credit :100$ Debit accout: 100$

Returns sales order:

This is done with reference to the sales order

Return Sales order has been created with reference to sales order : (sales doc number:AAAAS)

Qty :1 Value of the product =10$ Material: Ax001

A manual condition type is defined to reduce the value of the actual price .. The company is planning to give only 5$ for the return material

Manual condition has been included in the Return saels order Total net Value = 5$ qty = 1

Credit memo has been created : for 5$

Accounting doc: Credit account = 5$ debit account =5$

Issue: The account team wants one more account document to be created for the original value of the product i.e 10$

The net value in the billing document must not increase, but the account document must be created for the value=10$

This is for nullifying the original value of the product from the book of accounts

Solution tried : Manual condition for the original value =10$ keeping it as statically condition type : issue: account doc will not generate if it is statically . CND ref: 100% discount it did not work the net value in the order/billing is increasing

Please let me know how to generate the Accounting document with out increasing the net value.. Using standard SAP. we can create a routine and we can do this .. but we are looking for the Standard SAP solution if any,.....

Thanks for your help in Advance

Chandra