Invoice against Project delivery.

Hi,

We are delivering by projects and we are using milestone billing which is linked to SD. When i am trying to raise invoice, it is showing full billing amount even i deliver partial quantity.

For eg: i need to deliver 5 items to customer worth of 10,000. But i deliver only 2 qty by project. When i am trying to raise an invoice via VF01, it is giving full amount. But i need to raise only 4,000 for the 2 qty. Is there any way to restrict the billing amount respective to quantity delivered.

Kindly provide any solution for above scenario.

Thanks and regards,

Sesha