Business partner Customer fields update

Hi,

I am facing the following problem on Business partner master.

I am working on CRM 4.0

I am trying to migrate the business partner data from legacy system to CRM using the function module BAPI_BUPA_CREATE_FROM_DATA. But at site in the business partner master, some customer fields have been added using Easy Enhancement workbench. These fields become part of table BUT000 but are not part of the interface provided by the function module BAPI_BUPA_CREATE_FROM_DATA. Has anyone faced such problem or can anyone help on this issue on migrating business partner data when it has been enhanced using customer fields? What is the best way of migrating data in this case?

Also is there a 'direct input' way of CHANGING the business partner master data for Z fields ? The function module BAPI_BUPA_CENTRAL_CHANGE offers change to SAP standard fields. But we need to change the data values in Z(customer) fields.

Regards,

Vin