The World Federation One Stop Fiqh

Ruling 1397

If the link person in the congregation is a mumayyiz child – i.e. a child who is able to discern between right and wrong – then, in the event that the people in the congregation do not know his prayer is invalid, they can join with him. The same applies if the link person is not a Twelver (Ithnā ʿAsharī) Shia, in the event that his prayer is valid according to his religious denomination (madhhab).