Hi Satya,
The Bill of Product for Customs Management (CuMa) is not related to the BoM for Risk & Compliance. I guess it's because only customs-relevant components need to be taken into account for CuMa.
I don't think there are any tools provided for automatic transfer of CuMa BoPs. You can specify any BoP ID that is unique and numeric - the system does not generate it for you. If you don't want to create the BoP as Master Data in GTS, you can flag the Customs Product for "external BoP" - in that case, you must code the BAdI to obtain the relationship between the Finished Product and its Components, and you could write an RFC to interrogate the feeder system for that information.
Regards,
Dave