Q. Re- questions above (4383 – 4384) on a six year old being part of a minyan in order to recite kaddish. Re – the recent question of using a katan for minyan, doesn’t the Mishna Berura say that the kaddish after Aleinu cannot be said even when relying on the katan.

Rav Shlomo Miller told me previously that under no circumstances can the katan be counted. 
Rav Shlomo Miller Shlit’a said not to use katan in all cases. The kaddish after Aleinu can never be said with a katan. Why do you publish things that seem to suggest otherwise?

A. If you have likely noticed by now, we offer in our answers besides Horav Shlomo Miller’s Shlit’a opinion, the rulings of other Poskim and Rabbonim that disagree and are either more stringent or lenient. This answer quotes those opinions and mentions those sources.
Horav Shlomo Miller’s Shlit’a opinion is that in such a case it is better to recite an additional Yohrzait kaddish by Mincha.

Rabbi A. Bartfeld as revised by, Horav Dovid Pam, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a