Q. Can (a grandmother who in avelus during the year) attend a bar mitzvah of a grandson where music will be played (she has greatly helped in making the simcha)?

R. Horav Shlomo Miller’s Shlit’a opinion is that she is allowed to attend if she also serves the guest and she contributed significantly to the seudah, as it is seen as her own simcha. However at the time of dancing she should leave.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a