Participation in Daughter's End-of-Year Party During the Year of Mourning

Can a woman in the year of mourning for her mother participate in her daughter's end-of-year school party where there are programs and music?

According to the instructions of our teacher, Rabbi shlita, she can participate in the end-of-year party. When there is music, she should step outside (if the daughter does not need her presence at the party, she should not go).

Since the mourner is not present at the party for a friendship meal, but to show her daughter love and care, it is similar to what the Rema wrote in Siman 391, Section 2: "There are those who permit a mourner to eat at the fish meal made after a wedding, because since they have ceased to say that joy is in His abode, it is recognized that there is no joy in that meal, and it is permitted (Beit Yosef in the name of Rokeach)." Similarly, here it is evident that this meal is for the child's sake and not for a friendship gathering. Moreover, mourning within twelve months is due to honoring father and mother as stated in the rulings, and certainly, the grandmother's wish is that her daughter participates in this party, so the child does not feel abandoned and neglected.