Hi
You can also try with badi LE_SHP_DELIVERY_PROC, method CHANGE_FIELD_ATTRIBUTES. Read the documentation, changing the values in CT_FIELD_ATTRIBUTES for any name you could achieve it.
I hope this helps you
Regards
Eduardo
PD: I forgot, use also the method CHANGE_FCODE_ATTRIBUTES to avoid the user can push the element BT_WADR_T (fcode WADR_T)