Answer: suggesting MDM solution and also linking MDM to both the salesforce and sap. More so, integrating SAP with both Salesforce and legacy CRM.
NB: Don't ever integrate legacy CRM to Salesforce
Step-by-step explanation:
It should be noted that the best recommendation that could be given in order to keep data in synch b/w Salesforce, legacy CRM and SAP is by suggesting MDM solution and also linking MDM to both the salesforce and sap. More so, integrating SAP with both Salesforce and legacy CRM.
NB: Don't ever integrate legacy CRM to Salesforce