Can folders have a the [qty] and [unit] property exposed and assigned through formula or text?

What I am curious about is taking of a group of things off a schedule that I ultimately want to sum into a single thing. Many Footing types -> one Footings quantity. So below the F-4, F-5, CF-2, etc could be aggregated on the folder level. The idea would be if the [qty] variable that shows up in the report can be set by a formula which adds all the items I want that are child items, then the folder itself would become the quantity that I am seeking to control. The complication would be the number of items I would want summed would vary by project, and there could even be other sub takeoff like count and such that I would want to ignore in the total. If it is set by a function maybe there is a way to Add IF (some criteria).

Maybe there are other ideas out there for how to accomplish this that I am not aware of, I am open to any suggestions.

Thank you!