Hi Sree,
Recently I also worked on a new CO-PA data flow. Let me share how I have done it.
The CO-PA configuration of the Operating Concern is the starting point. I suggest to replicate the configuration as complete as possible. Generate the CO-PA DataSource as follows: all active Characteristics, all Line Item Characteristics, all Value Fields, all Calculated Key Figures (optionally, you might want to do it in BW), and all Fixed Fields. This will expose the maximum of data on the lowest granularity (i.e. document level).
In the Data Warehouse Layer you create a DSO containing InfoObjects for all extracted fields. I used my Data Warehouse InfoObjects approach to generate all InfoObjects. Please refer to Generating Data Warehouse InfoObjects - Part 1: Introduction for more information.
In the Architected DataMart Layer you will experience that Characteristics exist already to a large extend. E.g. Material related and Customer related but also Controlling related. You will have to create some custom Characteristics for the new objects (of course with the dependent requirements in terms of attriutes, texts and possibly hierarchies).
The Key Figures will have to be created from scratch. I used LSMW for that because there were a lot of Key Figures to be created, based on the same Key Figure definitions but with different descriptions.
I exposed as much as possible, i.e. all Key Figues and Characteristics in the following Dimensions: Material, Customer, Organization, Sales and Controlling (not taking the standard dimensions into account).
Best regards,
Sander