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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Muslim jurists mentioned that the sacrifice offered on behalf of a dead person is distributed in the same manner the sacrifice offered by a living person is distributed in terms of giving in charity and eating from it, and the reward goes to the dead person. But according to the Hanafi scholars it is prohibited to eat from the sacrifice offered on behalf of the dead person upon his request.
However, many Muslim jurists are of the view that it is desirable to divide the sacrifice slaughtered by a living person into three portions; he eats one third (with his family), gives one third in charity, and gives one third as gifts. Ibn ‘Umar was reported to have said: "Hady (sacrifice made by pilgrims) and (other) sacrifices are divided as follows: one third for you; one third for your relatives; and one third for the needy people." This is also the opinion of Ibn Mas‘ood and none of the Companions was reported to have said otherwise. For more benefit, refer to Fatwa 117201.
Allaah Knows best.