Hi Shan,
BYD is a Just-in_Time system (JIT). Which basically means that the system will backwards schedule the production from when you need it - with no buffer.
What are you trying to accomplish? - are you trying to set up the production as a make-to-stock?
I suggest you review the planning procedure together with the safety stock, safety lead time, etc., in the product master, with the intent to combine it in such a way that you achieve your desired result.
Hans