editing/creating new default formations in Editor

Would it be possible/feasible to have this feature added to the Editor?

That is, let's say you didn't feel a certain preferred formation assigned to a manager in the database best described the way he set up his team, and you didn't feel any other option described it well enough either, so you wanted to edit a new formation to assign him, would that be possible?

I guess this would be especially helpful in assigning asymmetric formations, as that makes many more permutations, whereas now there seems to be only one particular asymmetric formation in the default menu, based on Man Utd a couple years ago.