I had a doe that killed and/or neglected her first litter. I tried to save the last few, but sadly they all died. I also attempted to inervene, by holding the mom over them and through the use of a small pet nurser... but it was very difficult. It's very hard to bottle feed them without accidentally causing them to aspirate the formula. I had better luck with some wild bunnies that were a bit older, using canned goat's milk. Domestic rabbits have different nutritional needs, however. I've heard that most breeders use KMR kitten replacer in cases like yours. The stuff you got from the vet sounds good to me. I hope you have better luck than I did with babies that young.