Notification of Father's Passing on Purim

My grandfather passed away on Purim (with the burial after Purim). Should we inform his son who is not in town, or is it better to wait until after Purim?

To avoid ruining the joy of Purim and to avoid the dispute over observing mourning on Purim, it is preferable to wait until after Purim if there is no need to inform him for the burial arrangements.

Shulchan Aruch, Yoreh De'ah, Siman 402, Paragraph 12: "If someone has a deceased relative and he is unaware, it is not obligatory to inform him; even if it is his father or mother; and it is said: 'He who spreads rumors is a fool' (Proverbs 10:18). It is permissible to invite him to an engagement, wedding, and any joy, as he is unaware. However, if he asks about him, one should not lie and say: 'He is alive,' as it is said: 'Keep far from falsehood' (Exodus 23:7). The Rema writes: 'Nevertheless, it is customary to inform sons so they can say Kaddish; but for daughters, there is no custom to inform them (Mahari"v, Siman 13).'" Pnei Meirot, Part 2, Siman 100, and Pitchei Teshuva, there, Sk 2: "I ruled in a case where someone's mother died, and he was unaware, and an hour before Purim, his household learned and asked me whether to inform him so he could say Kaddish. I ruled not to inform him until after Purim, as there is a dispute among the rabbis whether mourning is observed on Purim. According to Shaalot, mourning is not observed, like on Yom Tov, but the Ram of Rothenburg disagrees, saying mourning is only canceled in private matters. Although we follow the Ram's opinion, it is better not to inform to avoid dispute, as by law it is forbidden to inform even about a father, as mentioned in Shulchan Aruch, Yoreh De'ah, Siman 402. However, the Rema writes that it is customary to inform sons for Kaddish, so in such a case, it is better to break the custom and follow the law, and 'sitting and not doing' is preferable." And obviously, if it is necessary to inform him for burial arrangements, it is certainly required to inform him.