corent

Hi I have created one product via API and also created one addBillableitem.Now i need to map this billableitem to that product via API. I have seen an option in GUI to map the billableitem to product. But i could not find any option in API to do this. Also i need the invoice for billableitem with the product's invoice. How to acheive this through API. Please reply asap, thanks in advance Regards Nageswari.S