Business Partner to vendor: mandatory fields

Hello,

We're on EHP7 FOR SAP ERP 6.0

for certain account groups, the field LFA1-STKZU (Liable for VAT) is mandatory. In the business partner field group 114 - Numbers for Taxes and Reporting, table DFKKBPTAXNUM, I don't see a similar field.

for others, the field natural person (LFA1-STKZN is mandatory, this field is available (DFKKBPTAXNUM-NATPERS)

.

How can I add the first field?

Likewise, How can we add Z-fields to the transfer?

kr

Nico