There should be the ability to measure something as a negative. We use this often for alternates where the scenario requires us to measure an item that is modified layout. Base Estimate has layout a certain layout, then the alternate needs to deduct some of that layout and extend in a new direction. So the alternate tracks the net change. The positive negative should be able to be applied to each measurement instance, not the whole assembly. So within the same assembly I can have both positive and negative measurements.
I work a lot with openings. So I had to look for a way to take negative measurments.
In the past what I did is taking a linear/segment takeoff with height. You see, I discovered a way to "cheat" the system, it's possible to introduce negative heights so the "Wall Area" would turn around as negative measurement, and appropiate for opening deduct.


With a new feature introduced a few days ago. Which gave us the chance to convert takeoff into independent itmes. I was able to add an "Opening Factor" you can call it "Deductive Factor" or as you prefer. With this factor I can configure my formula for this item to reflect the measurement times the "-1" deductive factor. This is far way more comfortable to work these dedeuctive measurements.


I hope my case is useful for you. You can look which of them is more fitable for your needs.
Regards.