What is the ruling on a person participating in an Islamic competition with the names of his family members, and some of them winning prizes, and leaving the value of the prizes to them as assistance?

Participating in competitions using the names of others is considered cheating and deception. The Prophet, peace and blessings be upon him, said: "Whoever cheats us is not of us." It is not permissible for someone who has done this to keep the prizes they obtained. Rather, they must be returned to their rightful owners. If that is not possible, they should be given to the poor and needy with the intention of charity on behalf of their owners. If your relatives, to whom you left the prizes, are poor and needy, there is no harm in leaving them for them. Otherwise, they must be given to the poor and needy, along with sincere repentance.