Q. My father recently died. As a daughter I joined in saying Kaddish. Was I wrong?
A. It would have been a good idea to clear it with the rabbi first, as not all rabbis are in favour. But I see no problem in principle. There are enough rabbinic precedents to go by. When my wife and I went to services at houses of mourning, she would often encourage the women mourners to say Kaddish and she went and stood beside them to help.
The Mishnah has no objection to women saying prayers and indeed mandates it (B’rachot 3:3). How can anyone say that a human being should not give voice to their love of God? There are differences of opinion as to how many times a day a woman should say an Amidah (Shulchan Aruch, Orach Chayyim106), but the basic obligation to pray certainly applies.
A daughter will feel better to say Kaddish and to know that she is spiritually helping the repose of the departed’s soul, though in the synagogue this should not be done in the men’s section unless by a girl under 12. At home or amongst the women it can be done at any age. There have been great rabbis who had no sons and left a request for their daughter/s to say Kaddish for them.