Hi Jürgen,
still guessing it´s the Default entitled from /SCWM/LGNBP.
A BP can have all 3 id types in Standard as BP can be a "representative" of ECC vendor and ECC customer and plant. The mapping of ECC vendor and customer is done in TX BP in the tab "identification".
For the maintenance of the BP with the 3ID types you might Need to Change some BP customizing settings. Pls check SPRO-Cross Components-SAP Business Partner-Business Partner-Basic Settings- ID numbers - define id types and remove the flag "Display only". This should enable you to maintain the entitled BP with all 3 ID types.
Check this and try again.
If it´s not working let me know which System and i can check.
Cheers,
Matthias







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