BADI's in ME21N

We have created a tab on the PO with some custom fields. However, some of these fields drive the account assignment. Is there way to call IF_EX_ME_PROCESS_PO_CUST_{PROCESS_ACCOUNT to execute our custom logic for account determination or set an indicator after the processing our custom screen in IF_EX_ME_PROCESS_PO_CUST}PROCESS_ITEM has been processed?

What we are finding is that IF_EX_ME_PROCESS_PO_CUST~PROCESS_ACCOUNT is only executed once unless something in the accounting data is changed. Therefore, when something else is changed on the PO in the custom part, accounting is not getting redetermined.