Is giving sadaqah in the form of sweets and juices to young neighborhood girls who are of moderate means considered a permissible sadaqah?

What you are doing by giving charity to these young girls is among the acts of goodness and righteousness, and you will receive two rewards for it: the reward of honoring a neighbor, and the reward of charity. The fact that they are people of wealth and comfort does not prevent this, because voluntary charity is permissible for the rich, and its giver is rewarded for it, even though it is better to seek out the poor and needy for your charity. As for obligatory charity (Zakat (definition)), it is not permissible to give it to the rich.