All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is not a condition in expiating for an oath that the poor be adult; rather, it is permissible to feed young children who are poor; Al-Buhooti from the Hanbali School of jurisprudence, said: “A person who is obligated to expiate has a choice to do one of the three following matters: feeding 10 poor persons who are Muslim and free [not slaves] even if they are young, or clothing them [the 10 poor people] or to free a Muslim slave…Whoever cannot find this, i.e. if he is unable to free a slave, or feed or cloth ten poor persons, then he should fast three days.” For more benefit, please refer to Fatwa 102811.
Allaah Knows best.