I always offer prayers for someone who's died. I don't know if it does any good...but I do it anyway. I figure it can't hurt. Do I believe we can help the deceased in any way? Not really. But I'll keep on praying.
Your intent is good but it will no longer benefit the dead!!! God's judgment is based on the acts of the living whether these are good or bad!!! The dead can no longer do anything under the sun!!! So, only the action of the living is the basis for God's reward or punishment!!!
You can only help the living person but not the dead!!!
Real Elias Ibarra