Gradebook

When my teachers go to mark an item as extra credit in the Gradebook Set up view, once in a while they check off the wrong box under Parent Category. There is a Weight Adjusted box, and an Extra Credit box.

So I was aiming to be proactive here and hide it out of view like other options on that Grade Item page (so this way, it will appear in the "Show More"). Unfortunately, Weight Adjusted and Extra Credit seem to be the only 2 things on this page that are not on the Advanced Grade item list. Everything above and below these 2 are in the box to select, but I was hoping to find a way to add that Weight Adjusted box as an the Advanced grade item. 

I did see "Aggregation Coefficient" in the list, however I don't see that particular item in the Gradebook set up page, not did selecting it make any change on the Grade Item page.

Does anyone have any suggestions?