To be honest, I'm very much confused by this business process. If you are creating production orders for the sales order, then why do you also need to refer another production order at the same time? Why are components not determined based on the sales order? And why do you need to "split" something? This looks rather odd, you might want to check with PP consultant.
Either way, there are only few BAPIs out there and their parameters are clear, so it is what it is.