Custom field in WPOHF4C and WPOHF4X

Hi Experts.

I want to add new column to ALV grid in transactoins WPOHF4C and WPOHF4X. I want to add this to header.

What I done:
1. Add new field to EKKO.
2. Activated in SE14

I tried to change FieldCatalog in BADI: WRF_POHF_X_UI_E (mtehod: CREATE_FIELDCAT_HEAD) like this:

CASE cs_fieldcat-fieldname.     WHEN 'ZZNEW_FIELD'.       CLEAR cs_fieldcat-tech.       CLEAR cs_fieldcat-no_out.

But:
1. Newly added to EKKO field not exist in FieldCatalog (so there is nothing to change)
2. When I tried it for some other field (standard EKKO field) fieldcatalog changed but screen didn't.

Do you know how to add custom fields to these transactions?

Regards,

Michal.