Hi Sanguine,
I'm afraid these functions starting with BUP_* are only supported in BDT, like for example, for when you're using CRM transactions like BP.
From where do you want to update? It is from an external system or WebGui itself?
If it is from an external system you can use BAPI_BUPA_CENTRAL_CHANGE by filling importing parameters BUSINESSPARTNER, CENTRALDATA and CENTRALDATA_X. Don't forget to call BAPI_TRANSACTION_COMMIT afterwards.
If from WebGui, you can access the BOL model and change it there (depending on each view you are in).
See if this helps you a little more 
Kind regards,
Garcia