Problem editing order by the admin

The customer bought a few items of goods at the store. After ordering asked me to order added another shirt.
If a customer bought a few items - it's the admin panel constantly displays the information (edition order) that the purchased goods by the customer is no longer available.

This is obvious.

Such a situation does not allow you to edit the order and apply the changes by Admin.
The same happens if the customer who bought the last pieces of the goods, asking for the removal of 2 position of the goods. Goods can be removed - but improved state can not be saved - as it always displays the information that the product is no longer available.

In such cases,

Go to order view page, then mark it as cancelled but don't notify client and click add history.
This will make the stock fill up again.

Now go to edit button and do the changes you want.

I know that this can be done but it does not make sense.
I can not cancel because the state of storage of the goods changes from 0 to 1. Then the goods will be visible to other customers who might buy it.

The problem is that even if I want to change the code or discount store to improve the delivery address does not allow me to save the changes.

On the Administrator - this should be possible, even if the state of storage is 0.

Another thing that I edit customer who bought the goods, which went down with the magazine.
All the time appear stars that the product is no longer available. It is obvious that it is not available because it was my client bought it.

I think it is a mistake store that you need to improve - because you can not normally use this function.

Sorry but admin also shall see the error if quantity is not in stock.
The way i said obviously has issues that quantity shall be visible for a short time period.
But if you do instantly it can work

There is extension for this. It allows admin to order from backend even when product is out of stock.
You can check this one: Stock help tools.