R/3 Sync to R/3 Sync Scenario

I have CRM (r/3) and DM (r/3)system.

Data from differnent tables of CRM system needs to go to

DM tables , data will be saved there and then return response back to CRM system.

I have one RFC for CRM system

This RFC has request parameters from where data goes to XI.

This RFC has response parameter which will save the response from DM.

I have one RFC for DM system

This RFC has request parameters which will be mapped to request parameter of CRM RFC.

This RFC has response parameter which will send response from DM to CRM.

So I have to make Sync Outbound Interface and Sync Inbound Interface.

So I think so no BPM is required.Am I correct?

So RFC--- XI -- RFC Sync approach.

Adapter -- RFC Sender and RFC Receiver Adapter. Am I correct?