Mass change of field WEBRE in table EKPO

Hi,

I would like to mass change the field webre in the table EKPO to space. But it is not possible with MEMASSPO.

The error message is MEPO025.

How is it possible to mass change this field? How can I handle it when there are already movements on the order?

Is it possible to change also the field ABELN and ADRNR?

Regards and thanks a lot in advance,

   Vanessa