Answer: At the end of the Shloshim (30 day period of mourning) for the holy Rebbetzin Chaya Moushka, o.b.m., the Rebbe gave over a talk in which he expressed it thus: “On the contrary, the main purpose of saying Kaddish Yatom is for minors, (G-d forbid,) as opposed to adults, whose activity for the merit of the soul of the deceased can and should be (mainly) through learning Torah, giving tzedoka, etc.” From the Rebbe’s words I learned (as well as from other sources,) that it is not appropriate for adults to argue over saying Kaddish, Haftora etc; and Rabbinical authorities have already discussed the matter of merit for the soul that comes about specifically through willingness to surrender the privilege of saying Kaddish to the next person wholeheartedly.It is worthwhile suggesting that when a mourner is prevented from standing up to be the Shaliach Tzibbur, or from saying Kaddish at a prayer service, he should try to add on to his learning in the merit of the deceased more than he was used to doing, and in this way he can make up for (and add on to) the missing Kaddish.