Answer
(Fatwa: 773/593/H=1431)
(1) Whenever and as much as you wish you can do isal-e-sawab by reciting the holy Quran, durood, offering nafl salah, keeping nafl fast, fulfilling the need of poor and needy one, giving money and articles in a mosque and madrasa and doing any good deeds by making the intention: O Allah give its reward to my father or so and so person.
(2) Keep on delivering the reward on the abovementioned pattern and also regularly make dua for his maghfirat (forgiveness).
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband