Item allocation / deductions

Item allocation / deductions

We have many sales orders which cannot be shipped or invoiced perhaps weeks or months in advance but we need to allocate items for these sales from non replenishable stock items.
This leads to major problems when we get another order for the same item because we tend to use this item as it's showing sufficient stocks because it hasn't been deducted through the earlier sales order not being invoiced or shipped !

As I've mentioned previously - I'd like to see another mode of stock tracking - "Receives minus sales orders" or even an additional row on the item page - "Qty on sales order", before the "Quantity to be shipped" line !
But knowing Zoho - none of this is likely to happen, so .....
Can any of you genius Zoho guys think of a solution that I can't ?