Custom ADR

Hi,
One of the customer requirement is as follows:-
The Material to be Return back as WIP Return and Credit should happen after the completion of  Repair.
So WIP Return will be with same Dr/Cr and later if we move for Repair to Main Store,
 the Dr should be Inv A/c  and Cr Should the WIP Return A/c.

Based on the following documents we tried to modify.

How To Derive Accounts Using Account Derivation Rules in R12 SLA Architecture (Doc ID 797115.1)
OPM Oracle Process Manufacturing SLA Subledger Accounting Setup (Doc ID 822303.1)

Modification of SLAM will be the best way to achieve and  we tried by defining a constant account at ADR  level but here the requirement is that Inventory valuation account