I am aware that in the past more than one rabbi was called by the title "Gaon" after his death. But the most known one is the Gaon of Vilna, Rabbi Eliyahu of Vilna. Does anyone know when and why he came to be called by that name as compared to other people? And is there a known description of the lines of descent >from Rashi under various permutations of the name Shapiro/Shapira/Spira etc. into various regions, in particular White Russia?
