Q. We started our small shul about twelve years ago and we have been successful. Recently a group of more Chassidishe friends joined us and we are pleased with their presence.
We have a Shaila, this new group has a minhag that on Shabbos Shirah they all sing together the Shirah. We never did that before.
Two questions. 1) Is there an ‘Inyan’ (worthwhile) reason to sing the Shirah together?
2) Although the majority of our Mispalelim agree to do it, is it permitted to change an already established Minhag?
A. 1) On question 135 regarding reciting the Shira with joy during a time of Aveilus, we wrote: “Zohar (B’shalach and Terumah) and Midrash, quoted by many Poiskim, exalt the ones who recite Shiras Hayam with great joy, with detailed care, and with its cantillations. They are considered as if they experienced themselves the Exodus of Mitzraim and Hashem saves them and forgives all their sins. (Pri Chodosh, Mishna Berura 53, et. al.)
Because of the inherent requirement to recite the Shira with happiness, some Poiskim advise to refrain from saying it in a mourner’s house or on the 9 of Av (Tur O.C. 559, Bais Yosef and Darchei Moshe ibid.). However, the accepted tradition is to say it including when the Avel himself leads.”
Therefore, in principle the minhag that all sing together with great joy, has a definite background.
Horav Shlomo Miller’s Shlit’a opinion is that if the majority want to sing together from now on, and it will not bring to a Machlokes, there is no reason why it should not be done.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller, Horav Dovid Pam and Horav Aharon Miller Shlit’a