Short answers, pulled from the story.
Journalists Sergey Lapenkov, Sergey Kolotovkin and Igor Dmitriev established the 9th of May 2012 as the birth date of the modern Immortal Regiment movement. A column of Tomsk residents passed through city streets carrying placards with photographs of relatives who fought in the Great Patriotic War on that day.
Director Yulia Sinelnikova conceived this procession to honor dead sons who had served in the Great Patriotic War. Mothers dressed in black robes marched on the Square of the Fighters of the Revolution in Rostov Oblast by 1981.
Forty-two countries hosted some form of the procession in 2016. The event spread to former Soviet states beginning in 2013 when it first appeared in Belarus and Ukraine.
On the 19th of April 2024, Head of Republic of Crimea Sergey Aksyonov announced cancellation of both parade and Immortal Regiment march for security reasons. Four days later Elena Tsunaeva from organizational committee confirmed Russia decided to cancel the march entirely due to fear portraits of those killed during the Russo-Ukrainian war would be carried leading to anti-war protests.
Vladimir Putin carries a portrait of his father Vladimir Spiridonovich Putin while Aleksandar Vučić carries a portrait of Anđelko Vučić who is his grandfather. Benjamin Netanyahu holds a portrait of Hero of the Soviet Union Wolf Vilenski who died in Israel in 1992.