How to justify balance amount of Accual Account (invoice not received) ?

We use OPM, PO and financials modules ;

Purchase order are created under PO module (Expense account is populated during the creation) and when corresponding receptions are created, System generates journal accounting entries (Accrual / Expense Account) ; Reception/purchase order are matched with payables invoices and the system generates journal entries for the invoices (Liability for the total amount including VAT / Accrual account + VAT) ; We have some difficulties to justify the Balance of Accrual Account (in france 408xxxx account -invoice not received) ;

I've tried 2 solutions :

1- I've tried to customize SLA rule in order to populate the GL Reconciliation reference directly from Subledger (with the PO number) :