PO exit to update FOC flag to all PO item

[Aeillaz]

Hi.

There is a request to update FOC (Free) indicator to all PO items if meet the FOC criteria.

I have tried using BAdI ME_PROCESS_PO_CUST (MEPOITEM-USMON = X), but it is not covering all scenarios:

method PROCESS_HEADER --> not triggered if no PO header change

method PROCESS_ITEM --> not triggered if no PO item change

method CHECK & POST --> it triggered for all steps but the update seems not working. If we display again the PO, the FOC indicator is blank (not updated)

I found exit EXIT_SAPMM06E* but mostly are for custom fields.  Other exits are more to validation.

Pls advise. Thanks