FYI: HaChossid Reb Yoel Kahan שליט"א is בא"ב of Rav Refoel HaCohen זצ"ל of Hamburg
בא"ב = Ben Achar Ben.
RRH was a Talmid of the גר"א who traveled to the Mezritsher Maggid and later refused to sign the ח on Chassidim. He was Rov the famous 3 Kehillos of אה"ו in Germany. I read this in a biography of his Brother-in-Law, Reb Boruch .פאריז, ע"ה