Issue with quanity in production

Hi,
We are trying to create a manufacturing order from the sale order. The quantity in the sale order is 15. However due to the limitation of the size of one of the raw material, we always get even number of products from the production, hence the BoM is set for 2 quantity.
We follow the workflow Sale Order --> Material Request --> Production order. Now when we

  1. set the quantity as 15 for the item to be produced, it gives an error that item in the BoM cannot be a fraction

  2. set the quantity as 16 for the item to be produced, it gives an error that produced qty cannot be more than sale order.

    How do we resolve this issue.

regards,

Amit