Is it also possible that mom didn't really reject them? If this is a dog breeder, maybe they are expecting the mother rabbit to lie with her babies just like the mother dogs do. Mother rabbits ignore the babies except for when they feed them for 5-10 minutes once or twice a day. To the unknowledgable person, it seems like the mother has rejected the babies because she completely ignores them.
If the mother was still feeding them I would request to get the mother as well. Then you can help her to feed the babies. Placing her ontop of the babies two to three times a day for about 5 minutes for the babies to feed. That should be enough for the babies to get fed, and to stimulate milk production.
Your best chances of having the babies survive is to feed them from mom.
--Dawn