Hi Nadeem,
I do not fully understand what you try to achieve? Why can´t you setup a new movement journal that has no default offset account setup and simply import/enter yours there?
I am not sure but it sounds as if you want to insert the loss account number (right?!) that would automatically be used if you use an inventory adjustment journal. Have you tried using this journal type?
After posting your inventory journal you can identify the transactions that have been posted on the ledger accounts by checking the item transactions and then checking the physical/financial vouchers created.
Would be good if you could provide some additional information.
Many thanks,
Ludwig