How to integrate the custom fields from CRM to business central

Hi All,

This is Mohit Malik, I am working on the D365BC and D365 CRM Integration, I am D365BC developer and for setup integration I have used the Common Data Services setup with D365 Integration setup. all things are working fine but we have some of the customized tables and fields into sales order table in CRM side which i want to take into business central. could anyone of you give some idea how I can achieve the goal, also could you please tell me from which object I can see the code where CRM entring the data into business central tables, like CRM accounts, CRM Sales order tables.