Can you provide sources for who says the kaddish-the baal kriya,the oleh, or anyone who is a chiyuv,even without an aliyah?
There are poskim that are of the opinion that the baal koreh is the one who says the kaddish, (see Gesher Hachayim 30-8(2), Shar Efrayim 10-9), however if he wants, he may give it to an avel to say. Others however say that the kaddish is really for an avel to say. See Sdei Chemed Dinei Kaddish 5-163 in the name Agudas Aiyzov,and Tashbetz 3-171, Shevet Halevi 8-163(3), see also Eishei Yisroel 38 ftnt. 120 that R’ Chaim Kanievsky shit”a wrote in the name of the Chazon Ish that this kaddish should go to an avel. Regarding a avel saying this kaddish even if he didn’t get an aliya, Shar Efrayim seems to say that it is only if he got an aliya, however Gesher Hachayim, Sdei Chemed say that an avel can say it even if he didn’t get an aliya. See Eishei Yisroel ibid that R’ S. Z. Auerbach zt”l held that since this kaddish is essentially for those neshomos that don’t have someone to say kaddish for them, therefore if the avel got an aliya he can say it, however if he didn’t get an aliya he shouldn’t go up specifically to say the kaddish.