Until 1772 the last Rabin was Symkha Rapaport, the son of the Rabin Khaim Khakoen Rapaport, the Rabin from Lviv.
https://shtetlroutes.eu/en/pidhaitsi-cultural-heritage-card/
Our Simcha is too yang.
More likely it was his cousin Simcha Moshe son of the Arieh Leib (brouther of Nachman).
