This coming Shabbos there is a person who has yahrzeit for a daughter (on Shabbos) and another person who has yahrzeit for his father during the coming week. Does the yahrzeit for the parent during the coming week supersede the yahrzeit for the child “Bo Ba’yom” as far as davening for the Amud? Who has the rights for the Amud for Shacharis, Musaf, etc? And in general is the “chiyuv” to daven for the amud only for a parent or for any relative that one must sit Shiva for, or for other relatives, as well (i.e. grandparent)?
The yahrzeit for a child supersedes the yahrzeit for the coming week with regard to davening from the amud.
Although it is customary for a person with an upcoming yahrzeit to receive the maftir aliya, and to daven mussaf from the amud, this custom is not an actual chiyuv, and will not supersede a yahrzeit.
The “chiyuv” to daven applies only to relatives for whom one sits shiva.
Note that some write that the custom of a yahrzeit does not apply for children under 13 who were niftar. See Tzitz Eliezer, Vol. 7, no. 49, Even Yaakov 6:7.