This is the Wikipedia entry for Stolperstein Project.

It says:
The Stolpersteine project, initiated by the German artist Gunter Demnig in 1992, aims to commemorate persons at the last place that they chose freely to reside, work or study (with exceptions possible on a case-by-case basis) before they fell victim to Nazi terror, forced euthanasia, eugenics, deportation to a concentration or extermination camp, or escaped persecution by emigration or suicide As of June 2023, 100,000 Stolpersteine have been laid, making the Stolpersteine project the world’s largest decentralized memorial

September 9 is scheduled for a memorial to Ellen’s family in Bad Homburg (Rothschild/Strauss). This is the website for Bad Homburg group