I heard that Rav Schwab used to walk with his sons to shul on Shabbos. One Shabbos a car came barrelling down the hill and killed his seven year old son. Rav Schwab insisted to the family that they stay happy lekavod Shabbos.
I heard another similar situation happened in 1990. There was a fatal accident on Purim night involving yeshiva boys. The levayah was on Purim and after the kaddish was said, Rav Schwab reminded the community that there’s a mitzvah of Simchas Purim and mourning must wait.