[cypher]

They both look very sweet

35g is small, how long since you separated them? If it was recent it may take Caroline some time to catch up with her weight as one will sometimes prevent the other from getting adequate food, even if it was some time ago she may never be quite as big as her sister.
What mix do you feed them?
It is unusual for a Russian not to like mealworms but you can give chicken, either plain cooked or dried as an alternative, dried shrimps are lower in fat than mealworms but still a good source of extra protein & most enjoy those.
Other than that a few extra seeds like sunflower, hemp, pumpkin & flax should help along with a tiny bit of nut now & then, walnuts & pine nuts are favourites with mine.