Does the zakat on joint property, paid on behalf of orphans, which is not obligatory for them, count as zakat for the coming year?

The correct view is that Zakat (definition) is obligatory on the wealth of a child, even if an orphan, if their share reaches the nisab (definition). The guardian must then pay it from their wealth. If the guardian does not pay the Zakat, the child, after reaching puberty, must pay the Zakat for the past years. What the mother did by paying Zakat for her young children is correct if the share of each of them reached the nisab. However, if she paid the amount with the intention of it being Zakat for the wealth of the minors, she is not permitted to count this amount as Zakat for her own wealth in the coming year.