Add an uncertainty with a negative sign on the production code, for example with the description «Expected saving». The final forecast goes down and the contribution margin goes up, without changing the budget. You can adjust or delete the item again whenever you like.
How to do it
Go to Prod. codes and open the production code.
Click Add and select Uncertainty.
Enter a description, for example «Expected saving».
Enter the amount with a minus in front.
Click Confirm. After a short while, you see the new final forecast and contribution margin.
When is this useful?
You want to see what the contribution margin will be if you only use part of a risk pool.
You expect a better purchase than estimated, but the contract is not signed.
Alternative
You can also add a planned purchase with an estimated amount on the code. The contract then overrides the budget in the final forecast.
Think through the reporting
Decide whether you want to report such expected gains, or keep them out until they are certain.