Hi Yuan,
The field 'Price Group' which you want to change the list values , is an element under the screen '4301'.
This field with data element 'KONDA' has a value table, that means the list values are populated from domain level.
If you see the flow logic of this screen(4301), there is commented line as below
"* MODULE T188T_SELECT. " Not used because Listbox".
But if you double click on this module, you will reach an include 'MV45AO0T_T188T_SELECT'.
I think ,from here if you explore more on enhancement framework may help you.( I did not tested/explored on this).
Regards
Pallavi