7 Remedies for overcoming pitra dosh
People who don't know the date of death of their manes can perform all these activities for pacification of their manes on the day of Amavasya.
If the person will worship the Peepal tree then Pitra will be removed. If he will offer Kheer to his manes on the day of Somvati Amavasya then Pitra Dosha will be removed. You can also offer food and clothes to Brahmins on every Amavasya to reduce negativity of Pitra Dosha.