Sadhabhisekam is one of the religious ceremonies done in Hinduism. It is one of the formal ceremonies (and can be called a duty to all children) done by the children to their parents, when the father reaches the age of 80.
The same preparation done for every marriage will be done for this also, like invitation preparation, food arrangements, booking of hall for guests.
References
Sadhabhisekam Wikipedia(Text) CC BY-SA