161. Shiva vs. Yahrtzeit
26:3 If there is someone with yahrzeit in shul, then if the mourner is a minor who goes to shul and will potentially be there every day of Shiva, then the yahrtzeit is given one Kaddish. (This is also the case for an adult who davens in shul during the week of Shiva – see Bi’ur Halacha 132, “Kuntres Maamar Kaddishin.”) If several people have yahrtzeit, each is entitled to a Kaddish, even if this leaves the minor without any. Someone in Shloshim is also entitled to one Kaddish in this situation but if there are many people in Shloshim, the minor will never lose every Kaddish because of it. An adult mourner who never goes to shul during the week because he davens with a minyan in his house is still entitled to all the Kaddishes when he goes to shul on Shabbos. If there is a yahrtzeit, the mourner says every Kaddish but one and they draw lots for it. If Yom Tov comes and cancels the mourning of Shiva, or if the deceased passed away on Yom Tov, then the adult is like the case of the minor because he will be davening in shul from then on rather than in his home. 26:4 A minor and an adult, both in Shiva, who come to shul on Shabbos, split the Kaddishes evenly between them. If there is also a yahrzeit present, he is superceded by the adult. The adult then receives one Kaddish more than the minor because the minor has to give one to the yahrzeit.