[Advaita-l] Death on a festival tithi

[ravi chandrasekhara]

Pranam,
If a person (X) dies on on the same tithi as Ganesh Chaturthi, Rama Navami, etc; then prati-varshbadika shraadha (annual shraadha tithi/death anniversary) has to be performed on that tithi. Then X'son(s) will not be able to perform Puja vidhi for that festival since they have to perform shraadha vidhi. But after X's sons pass away ( as long as not on the same festival tithi); then X's grandsons may resume puja vidhi for the festivaL.
That is what my father told me based on family  experiences. For example, one of my cousin's father passed away on Shivaratri hence he does not perform/celebrate Shiva puja on that tithi.
However, If person X expired on Shraavan Purnima/Yajur Upakarma; they when can X' s son (s) perform Yajur Upakarma ?
Dhanyavaad for responses.
Ravi Chandrasekhara