Hello Rahul,
The scenario you described is called MEP (Multi-system Exchange Projects).
SAP has a note 1084315 about the information of this kind of scenario.
As it mentions, only the master data objects, such as CUSTOMER_MAIN, CUSTOMER_REL, MATERIAL, BUPA_KNVH, and DNL_CUST_PROD1 are technically support. All the other objects and transactional data in particular, are not supported.
An MEP is usually highly customer-specific. Therefore, these landscapes require an in-depth knowledge of the scenarios to be implemented.
You can find the documentation in Solution Manager under 'Basic Settings for SAP
CRM' -> 'Multiple Systems Exchange Projects: Multiple Backends'.
Also, you could check the help document for the configuration of the MEP.
Configuring the Multiple Back-End Scenario - SAP CRM: Grundkonfiguration - SAP Library
Hope my answer helps.
Thank you.
Best regards,
Julin Xin