Are your bunnies indoor or outdoor? Indoor rabbits will end up shedding all year round because they are not exposed to the temperature changes.
I use timothy pellets and have no problem, but my bunnies are indoor and I find that at certain times they shed. But I groom them at least three times a week because I know they will shed all year around.
And also I make sure they have lots of hay and water, along with papaya to help fight any hairballs.
eta: Reread your post and it looks like they are indoor rabbits. You will find shedding a common thing and grooming will resolve it. Unfortunately I vacuum and clean all the time. If I want to stop hair year round, I would put outside so they shed seasonally. But, I love my boys and don't mind the clean up. But remember, the more you groom, the less you have to clean. And grooming is a great way to bond with your bunny.