Q. Someone who delivers a Daf Hayomi and in this year it will be on Sunday. Since usually he group learns two dafim on Sunday (Shabbos and Sunday dafim), it will be tough later on to catch up.
Is there a ‘Heter’ (permission) to learn the dafim on Tisha Beav, but including with them how they would apply in cases of Avelus or mourning?

A. Horav Dovid Pam Shlit’a stressed that learning the Halochos of Avelus or mourning although permitted during Tisha Beav, (Shulchan Aruch O.H. 551: 2) should not be used to permit other non related Torah learning. Only Torah material that relates directly to Avelus or the Churban of the Beis Hamikdash is permitted.

See Piskei Halochos 554: 4 n. 16.

However Horav Kalman Ochs Shlit’a pointed out that some Chassidic congregations learn the Daf after Chatzos (midday).

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