Can I do Pitru Paksha rituals while my parents are still alive?

Question

I would like to do Pitru Paksha rituals, such as offering black til seeds and water to my ancestors, like my grandfather and great grandfather and maternal grandmother. My paternal grandmother and my parents are still alive. Traditionally, it would be my parents who are the ones to do it, but my parents are not well versed in the rituals. Can I do it even though they are alive? I found a simple ritual online but I intend to do it while omitting the parts for father, mother, and grandmother since they are still alive.

The reason why I would like to do it, besides honoring my ancestors, is because I believe the problems me and all my living kins ( parents, aunts, uncles, cousins etc.) face is because of Pitru Dosh.

Answer 1

If the father is alive even then the son is allowed to do the ancestral offering for his deceased grand father, great grand father etc..

I thought that this was not allowed but see the following verse 3.220:

Manu Smriti 3.220. But if the (sacrificer’s) father is living, he must offer (the cakes) to three remoter (ancestors); or he may also feed his father at the funeral sacrifice as (one of the) Brahmana (guests).

3.221. But he whose father is dead, while his grandfather lives, shall, after pronouncing his father’s name, mention (that of) his great-grandfather.

Answer 2

According to Vaidic scholars in my city, the one whose parents are still alive can not perform these rituals you are talking about.

Let's see what you can do.... According to my Guru one should read Bhagvad Geeta's seventh chapter every day in Pitru Paksha and offer it's Punya to his ancestors by praying so. Also one should chant 1 mala of the Mantra ओम ह्री्ं श्री्ं क्ली्ं स्वधादेव्यै स्वाहा and also offer the Punya of the chanting to ancestors.

The Pitruloka's one day equals one year in here. So every year we should do tarpan in Pitru Paksha.