Answer for Pitru Tarpana while father is living:
(Called JivaPitruk I believe ):
Summary:
Give Tarpana to the ancestors excluding the living Pitrus.
In Detail:
For Pitru Tarpana while father is living, I believe Manu Smriti 3.220 gives the path:
Rough translation:
“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).
Manu Smriti 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.
Now… the difference of opinion comes here: the Gryhasutras then say that
“for one whose father is alive there is neiher Piṇḍapitṛyajña, nor Śrāddha;—there is either non-performance of these rites, or their performance only up to the stage of pouring libations into fire.”
Whereas:
Viṣṇu Smriti (75.1) says.—‘If one performs the Śrāddha while his father is alive, he shall offer it to those whom his father offers it.’
Thus (if either parent is living) then … the living father/ mother are obviously excluded while others in the lineage can be offered the Pinda daan and tarpana.
If both are dead, they MUST be offered the Pinda daan or Tarpana!
This is the long and short of what we say for Pinda daan and Pitru Tarpana.
@karshneya@mmpandit Last line is very easy to say than done. One may have to wait for decades just for the chaos to settle down but that very chaos is the fertile land for the accelerated spiritual progress which otherwise wouldn’t have been a possibility in lifetime(s)!