modifying quantity of an orderitem, results in wrong in stock count

[Netflyer]

If the quantity of an orderitem is modified in the backend the old quantity is subtracted on "Booked, ordered products", but the new quantity is not added.

I'm using VM2.6.6 on JM2.5.19

[Milbo]

Very hard approach. The system must also recognise if you change the order status or not. and which order status has the product. If you find a logic, we will be happy to add it for vm3

[Netflyer]

There seems to be a misunderstandig, I'll try it with a user story:
- There are 3 shovels in the shop (3 in stock, 0 on order)
- User orders 1 shovel (3 in stock, 1 on order)
- User calls and tells he wants 2 shovels
- Admin changes quantity in the order in the backend to 2
this results in (3 in stock, 0 on order)
expected result (3 in stock, 2 on order)
the order is in confirmed state, but it is also wrong calculated if in sent state