No one is irreplacable..

Day before yesterday was my material fathers srarddha ceremony. It has been 15+ years since I lost my father.  He was such a lovable, caring father treating me like a princess and I was like a Daddys daughter. It was a disaster when he left his body then. Well but now I realise no conditioned soul is irreplacable, be it you or me. Time will heal anything and everything. Krsna will make Some one or other to act as his instrument in the hands of the lord and everything will be taken care.

Anyway ...Srila Prabhupada says the following on Sraddha ceremony - "What is that prayojana? To get son. Marriage means to get son. That is prayojana. Putrayate kriyate bharyah. Bharya means wife. One has to accept a bharya, a wife, why? Putrayate. For the matter of getting a son. Why? Why there is necessity of getting a son? Putra-pinda-prayojanam. This is Vedic civilization. Putra. Putra means Pun-namno narakad yasmat trayate iti putra. Pu-tra. Pu means pun-namno narakat. There is a hell which is called put. So from that hellish condition, one who delivers, trayate iti tra, therefore he is called putra. This is... Every Sanskrit word has got meaning, root meaning. Putra. Putra-pinda-prayojanam. Putra is required. Why? After death, if by chance the father does not get ordinary life or goes to the hellish condition of life, the son will deliver. Therefore sraddha ceremony. There is sraddha... What is that sraddha ceremony? Sraddha ceremony means to offer foodstuff to Visnu, and with the prasadam, to the forefathers or father it is offered so that by eating prasadam, if he is in ghost life or in hellish life, he'll be delivered. This is called sraddha.So it is the duty of the son, to do sraddha ceremony".

My father was not so fortunate to come in touch with Krsna conscious movement. But atleast now we ensure that he gets krsna prasad during his Sraddha ceremony.For sure it should be helping him somewhere though we couldnt realise with our material senses.

Well whats the process for others ?

Srila Prabhupada continues, devarsi-bhutapta-nrnam pitrnam nayam rni na kinkaro rajan sarvatmana yah saranam saranyam gato mukundam parihrtya kartam [SB 11.5.41], Anyone who is fully engaged in Krsna's service, he has no other duty. He has finished all other duties. Tepus tapas te [SB 3.33.7]. This is the injunction of the sastra. He's no more anyone's servant, or he has got any duty to do -- saranam saranyam -- because he has taken the shelter of the ultimate Supreme Person. This is the injunction of the sastra. So this sraddha ceremony is not required for a devotee fully surrendered to the lotus feet of Krsna. Gato mukundam saranam saranyam. Saranyam: He is the only shelter. And who has taken shelter of Krsna, he has no other duty. This is the sastra.