We have added via CFL a custom purchase item field which will be populated with data while starting ME52N and ME53N and other purchase order and offer FIORI apps,
So we are looking for the BADI which can be used for this case,
But there is only this one MM_PUR_S4_PR_FLDCNTRL_SIMPLE which is treggred when opening the tcode or fiori apps.
Unfortunately the header and the item parameters of this BADI are in the input area and we cannot set data in the added custom fields to get values only displayed in the front side,