I saw your response "I am using the spsoAPISalesOrderIns stored procedure but it does not indicate to use any other staging table other that StgSOLine in terms of validating the header and details." , but it is not displaying on the website at the moment. 

If you reviewed the stored procedure, you would see it reads records from StgSalesOrder by session and process status.  The detail records in stgSOLine link to the header records in stgSalesOrder by TranNo and Session.  I am not sure where you saw only stgSOLine was used for spsoAPISalesOrderIns.  If you have DMT installed, you can use it to see what staging tables are used for each process or as I suggested previously script the stored procedure and review it to see what staging tables are used and how they relate to each other as well as what values to pass for each parameter of the stored procedure.. 

I saw your response "I am using the spsoAPISalesOrderIns stored procedure but it does not indicate to use any other staging table other that StgSOLine in terms of validating the header and details." , but it is not displaying on the website at the moment. 

If you reviewed the stored procedure, you would see it reads records from StgSalesOrder by session and process status.  The detail records in stgSOLine link to the header records in stgSalesOrder by TranNo and Session.  I am not sure where you saw only stgSOLine was used for spsoAPISalesOrderIns.  If you have DMT installed, you can use it to see what staging tables are used for each process or as I suggested previously script the stored procedure and review it to see what staging tables are used and how they relate to each other as well as what values to pass for each parameter of the stored procedure..