Three of my grandparents have passed away over the years. While I come from a traditional family, I am quite certain that none of my grandparents’ children are saying kaddish on the appointed yartzheit. Provided that I cannot convince my grandparents’ sons to say kaddish for them, should I take it upon myself to do this every year?

If you have both parents alive you should ask their permission to say Kaddish, if unfortunately not, yo may say Kaddish for our grandfather.