This is permissible. However, the sunnah is to slaughter only one sheep and include in it all your deceased ones.As for the prophet Muhammad salla ALlahu alahi wa sallam, you shouldn’t do that as  he is not in need for that and it is an innovation.

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You do the good deeds and ask Allah by saying: I ask You for I did so and so for your sake to do so and so for me.

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This is an innovation and it is not acceptable! He can ask Allah for forgiveness for his father, make umrah and hajj for him or give money in charity on his behalf.

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