Just provide lots of free fed good horse quality(no mold, never been wet, no noxious weeds) soft grass hay for them to nibble on. Grass hay is a far better first solid food for baby rabbits, as it's less likely to cause digestive problems than pellets do, due to baby rabbits difficulty digesting starches. Eventually they will start to nibble on pellets, but it's much better for them to do it as they get a bit older, and only very gradually to minimize the risks of it causing enteritis. And if you can afford a good quality pet brand like oxbow, sherwood, science select, etc, these will be less likely to cause digestive problems, than some of the bulk commercial pellets, due to the higher quality ingredients and lower starch levels.