I actually have had to cut my buns off pellets altogether at times when trying to find out what foods work and don't.
I only use oxbow bunny pellets (nothing else in it) and give both bus 1/4 cup for dinner. They don't need more than that.
Otherwise all they get is unlimited hay (which is most of their diet makeup) and a few veggies like Romaine, parsley, mint, kale, blackberry leaves, dandelion to make a few)