I want to add a new customer's detail to the new order created. As the customer is new we don't have its customer ID. We want to associate new customers details to the order we have created. Can we add other the details like firstname, lastname, phone number, email, billing address of the customer to the order? How do we do that without creating a new customer?
You need the customer ID to add the customer to an order. Without a reference ID there is no way to make this association. You would need to create a new customer and populate the information before closing the order.