Update Purchase Requisition EBAN Table from va01/va02

Hi,

My requirement is to Update purchase requestion EBAN table from Sales Order create/change.

In EBAN table i have two custom fields. Customer Article Number(ZZKDMAT) and Customer purchase order number(ZZBSTKD)

I have used Userexit :-MV45AFZB-USEREXIT_MOVE_FIELD_TO_ME_REQ

This user exit is triggered only in case of creating a sales order...not in case of changing the sales order through va02.

Please let me know any Userexit/BADI where I can Update Purchase Requisition EBAN table from va01/va02.

Thanks,

Vikas..