R’Moshe Ernster is a son-in-law of R”chaim Meir Hager zz’l , and a brother-in-law of R’Moshele hager zz’l , recently nifta, both Vishnitzer rebbes. Hence, he is the uncle of the present Vishnitzer rebbe, R’yisroel Hager shelita.
His son does lead the bais hamedrash in jerushulaim, which is ,of course, on the vishnitzer derech.