Hi,
Hay is the most important part of a bunnies diet, it should make up 75% of it, rest should be greens/ veggies/ pellets/ little fruit once in a while. You should cut down on the pellets. For a bunny that is 1-4lbs they should get no more than 1/8th of a cup of pellets and if 5lbs then 1/4th of a cup. Too much pellets is a bad thing, it leads to dental and health problems including them being overweight.
Feeding limited pellets is important because you want them to be hungry for their hay and greens/veggies that are really important. Pellets should not be main source of diet. In addition to limited pellets and unlimited hay they should get a min of 1 cup of 3 different greens/ veggies a day start them off slowly. Some that are enjoyed by bunnies are dill, cilantro, romaine lettuce, mint, endive, basil, parsely, green/red bell peppers, carrot and carrot tops, kale. You wanna offer 3 different daily for variety and always feeding the same greens can cause an imbalance in their system.
Another thing to consider is if your bunnies are getting to the point where they might be or soon will be overweight good to slowly switch over to a timothy pellet which has less protein, fat, and calcium that older rabbits over the age of 7 months do not benfefit from and dont
need. Some companies that make good quality timothy pellets are Oxbow, Kaytee, Sweet Meadow farms, martin mills (canada)
Take a look at this website contains some good information on diet and other things http://www.hrschicago.org/dietcarefr.html
Hope that helps