call orders: order confirmation by shipment?

call orders: order confirmation by shipment?

Hi all,
we deal with plenty frame orders, which we have to ship in lots as per request of our customers.
Our customers want  for each call order an order confirmation.
As far as we can see, we can only create an order confirmation for the whole order, but not for each underlaying call order - any idea how we could achieve this? 

in example:
sales order created of 100,000 pieces, saved, send and confirmed.
first shipment of 20,000 pieces is called of - packing and shipping can be done, but no confirmation of the call order can be done!
We could create new sales orders per call order - but this is affecting the accounting stock and demand/re-order figures!