Is there a way to add reverb to the voice in the monitor headphones while the person is singing? It wouldn't neccessarily record the reverb, but would give the singer reverb in the headphones.
You will need a reverb box that can be patched into the signal path to the headphones. If you have a mixer with reverb on it, the reverb will end up on the track, which is not necessarily a good thing. The software reverb won't show up in the headphones.