Restrict ECC to CRM order creation but allow to modify using middleware

Hi Folks,

We need to restrict sales order creation from ECC to CRM but allow to update existing one meaning if the order available in CRM table 'CRMD_ORDERADM_H' then allow to update if not then it should not create new order in CRM coz currently it is creating.

I know the badi 'CRM_DATAEXCHG_BADI' , but don't know which method is correct to restrict order creation by cleaning all parametere andalso it should not impact on existing design.

Can anybody help me on this issue.

Thank in advanced

Regards,

Nikhilesh