Is it valid to delegate the authority to divorce to a non-Muslim, a slave, a woman, or a non-discerning child?
Chapter on Explicit Divorce and Others
Al-Mughni
Book of Divorce
Primary text
It is valid to delegate the authority to a non-Muslim or a slave, because they are capable of effecting divorce upon themselves, making their agency valid in this matter. It is also valid to delegate it to a woman, as her agency in freeing a slave is valid, so her agency in divorce is valid, similar to a man. If delegated to a discerning child, the validity depends on whether the child's own pronouncement of divorce upon his wife is valid. Ahmad explicitly considered the child's capacity to issue divorce to his own wife as the measure for the validity of the agency. Similarly, if the authority is given to a minor or insane woman, she does not gain the power, unless she reaches the age of discernment, as established for the child.
Supporting text
There is another narration regarding a boy stating that his divorce is not effective until he reaches puberty, which implies that in this context, the divorce would also not be effective until the female minor reaches discernment, as they are equivalent in legal capacity.