Poonam,
So, it sounds to me like you are not going to be planning the components (since you have no visibility of the Subcon's lower level Materials on hand, nor his open Purchase orders, nor his demand for these components that is generated from customers other than you).
It really sounds like all you can do is to send him a list of your exploded demands for the Purchase orders that you send to him. Don't attempt to send schedule lines, which represent future supply. From what you have described so far, you don't have enough information about his internal affairs to give him any meaningful supply schedules.
This listing doesn't have to be anything more complex than a simple query or z report.
Best Regards,
DB49