We started with the replacement of SAP CRM by yC4C. Actually we have an integration of SAP ERP and SAP CRM. Initially in the past the ERP-Customers were downloaded to CRM. After go-live we switched the creation process and start exclusively in CRM. The number ranges are disjunct. Initial customer from ERP start with 1***** and customers from CRM start with 3*****. The mapping is stored in BUT0ID and visible in the WebUI. Once a customer was created in CRM with 3*-number in ERP it gets the 1*-number which is transferred to CRM (table BUT0ID). That's the background. Our allowance for yC4C-Implementation is to start standalone w/o ERP-integration. Integration will take place a few months later. My challenge is to migrate all accounts extracted from CRM to yC4C. But I am not sure how to guarantee (or handle) the future integration with regard to match the debitors in ERP with the accounts migrated from CRM. We cannot perform an initial load as the debitors will be already in yC4C as a result of the migration. Is there a mechanism in yC4C like the identification numbers and keys (table BUT0ID) in CRM. Do I have to expect trouble in number matching or is it no problem. Did anyone solve such a request?