It does sound like a first litter doesn't it ... the mother does not appear to be responding to the kittens and they don't appear to be responding to her as a food source. I think you are right with your suggestions but that maybe they need to be getting in that milk substitute as a matter of urgency. I would not like the kittens to have to go hungry much longer. Ideally they should suckle the mother if she has milk so that they can obtain the antibodies available through the colostrum (first milk), but if the mother is not supplying milk at all then alternatives must be found. I find it strange that the kittens are apparently fairly apathetic too - if they are in physical contact with their mother and not actively seeking food it suggests that they are either not hungry (ie suckling but not in front of strangers) or that they are, themselves in a fairly worrying state of apathy which may warrant a trip to the vet. Kittens fade fast if they are not getting nourishment ...
