Shraddh - Pitru paksh

Shraddha means faith and shraddh is related to it. Having faith that pitru lok exists and that the doors is open during pitru paksh is the crux during this time. Faith That they will receive your love and offerings and will rejoice in your happy life. As they want your lineage to continue as it is their lineage on earth . Without having faith no process of shraddh works.

Even though different kulas and types of devata worship was spread across the globe by Rishi ,Siddhas, one common aspect was ancestral worship be it Chinese ancestor qingming festival or in Mexico dia del los Muertos having the blessing of ancestors is very important and quickest way towards a happy life. before every sadhana or worship kul devata and pitri ancestors are invoked for success as. Hence no sampraday can claim they are monotheistic in that sense if you don't invoke them you can't even reach higher Gods.

Hell and heaven is Abrahamic concept . pitri lok is not purgatory of Bible which advises a soul waits to go up down heaven or hell. They are not preta either , pretas is separate yoni [ species] that reside in patal or rasatal. With Good karm and shraddh one can ascend to dev lok directly. A regular person after death and final sanskar [ refinement] goes to pitru lok , they live there until they decide to take a rebirth just in any other loka. Pitris are powerful species and can grant many boons to the living.

Take little water in your hand and say

Om sarva pitribhyo Namaha

and pour the water out.

Be grateful for their help and pray they can ascend . Keep doing shraddh so that they ascend to higher loka .

All my knowledge comes from my Guru Kaulantak Nath Ishaputra.

Om sam siddhaya Namaha

Om sri Padmapriya ramapati Ishaputraya Namaha

Om sarva pitribhyo Namaha