@butterw As I already said in the past, instead of Ctrl+A and Ctrl+D, I suggest having Ctrl+X and Ctrl+Alt+X, where X is any natural number. The number defines that only the units having that mobility value or more are added as long as they can attack ("fire"), respectively, as offenders or as defenders (so, Ctrl+0 would act the same as Ctrl+A).
The main advantage is that, when adding offenders, you use Ctrl+1 for adjacent zones, Ctrl+2 for zones which are not adjacent but are adjacent to an adjacent zone, and so on.
When adding defenders, you will probably almost always use Ctrl+Alt+0.
Of course, the feature can be limited upwards to the number 9.