Birthday party on night of Shiva Asar Be-Tammuz – Part 2

Last week we posted that Rav Aviner was asked if it is permissible to celebrate a birthday party for a girl on the night of Shiva Asar Be-Tammuz. Based on a Teshuvah of Ha-Rav Moshe Feinstein (Shut Igrot Moshe, Orach Chaim 1:168), he answered that while it is not preferable, it is not forbidden.

We received the following response from Ha-Rav Aharon Ziegler (author of "Halakhic Positions of Rabbi Joseph B. Soloveitchik" vol. 1, 2, 3 and 4):
Regarding the question of a party on the night of Shiva Asar Be-Tamuz, my Rebbe, Rav Yosef Dov Soloveitchik zt"l. felt that every Ta'anit (fast) has an element of Aveilut (mourning) (except Yom Kippur), with it. Therefore, although the actual "fasting" begins in the morning, the Aveilut part begins the night before. He cited the Gemara Ta'anit that discusses reciting "Aneinu" (a prayer recited on fast days) for Ma'ariv, although we are still permitted to eat. He therefore felt that the Aveilut of the "Bein Ha-Metzarim" (The Three Weeks) begins at night and a party would not be appropriate.