Saying Kaddish for the deceased is an obligation on the sons of the deceased, the purpose of the Kaddish is to help the deceased in the next world and therefore it is a very important mitzvah.
Even though the mitzvahs are the sons possibility of appointing a messenger to perform the mitzvah for you, but still try to say it yourself.

Yeshiva Hichal Meir, led by Rabbi Zamir Cohen, allows you to appoint as a messenger to speak a mitzvah a yeshiva student who will say Kaddish for your loved one in the year of his death, this mission does not involve a fee, but it is recommended to participate in it for some fee during the period of saying the Kaddish