If, Heaven forbid, a person's relative died during a particular year, then one must take care not to weep about this at all on the Seder eve, and the people of the household are not to agonize about this. One should gather one's strength and overcome one's nature notwithstanding; he, his wife and household should be happy and be strong and, with God's help, their luck will improve.
While we were still living abroad in the town of Amadiah, we had an excellent custom on this matter. On Passover eve, after the afternoon and evening prayers, or in the morning at dawn we would go to the home of one who was still within the twelve months [of mourning the deceased] and dress all the household members in festive garments, and go to the Passover festival prayers together.