Business Partner Creation for Sales Customer

Hello,

I am almost certain this question was asked before, but I couldn't seem to find the answer.

I have an external customer number that needs to be passed in from a 3rd-party system to SAP ECC 5.0 (part of ERP 2004). I could use BAPI BAPI_BUPA_CREATE_FROM_DATA to create the customer in BUT000 table. Since this is really a sales customer, I was hoping this customer can be duplicated/transferred to KNA1 table. Without doing this, this external BP # does not show up in my dropdown list when I create an order. I also tried to use BAPI BAPI_BUPA_FS_CREATE_FROM_DATA2 to create this external customer by adding a role "FLCU00", but I still couldn't find this customer in the KNA1 table. I also looked at a couple more options such as BAPI_CUSTOMER_CREATE and BAPI_CUSTOMER_CREATEFROMDATA1, but as far as I know the first one is online dialog mode, and the 2nd one does not seem to allow exteral customer number. Does any know whether it is possible to use BAPI_BUPA_CREATE_FROM_DATA or BAPI_BUPA_FS_CREATE_FROM_DATA2 to create an entry in KNA1? Is it more a config issue or technically it is not possible? Please advise. Your help is appreciated!!!

Regards,

Chao