How to change field status for standard field on adjustment screen at RE-FX contract using BDT

Hi gurus,

I'm about to modify the standard behavior of the field status for one standard field on

dynpro 1000 at REAJ_GUI_SPECIFIC_INDX function group, from modifiable to only display. And I would like to manage this change with a "standard" enhancement as per BDT. Or even a BADI would be on the scope. Instead of using implicit enhancements.

Does somebody know how should I proceed?

Thanks in advance