Feed formula results into final grade?

I need a way to create a formula column in brightspace that can then be entered into the gradebook as a new grade item in its own right. (Right now the results of a formula column just seem to serve a display purpose in the gradebook. I am totally unclear what formula columns are even for, actually, since their use is so limited ). For example, if I want to add 3 points to everyone's exam score and feed that new column into the final grade, I can't do so without exporting the whole gradebook as an excel file, writing a formula in excel to add 3 points, and then re-uploading the whole excel file back to the gradebook to create a new grade item from the adjusted column. While I have figured out how to do this, I am trying to easily train TAs every semester, and also I am deploying a module of assignments that is being designed for many teachers across many different sections of a course (where I need access to a "formula" result for final project grade computation) and I want it to be as seamless as possible. I would like to save the training overhead related to how to do excel exports and imports every semester. I am so confused why brightspace would choose to add a formula option to do the work right within the gradebook, but there would be no possible way to enter the results of that formula into the gradebook as a grade item in its own right (a grade item that can feed into the final grade, that you can exempt certain students from, that you can assign to a category and drop the lowest from, etc.) It is so confusing to me that an LMS would not have this functionality that I am assuming I simply must be missing an option. Any help would be great! I also give out daily participation scores worth 2 points, and rather than overwhelm students with dozens of daily scores in the gradebook, I want to enter those, but hide them from students, and just display a "weekly" participation score (sum of all the dailies) that gets assigned to a category where I can drop the lowest "weekly" score out of 13 weeks, etc. at the end.

There are so many things I would use this feature for! Am I missing a workaround? Thanks!