Unger was born to Yaakov Yitzchok Unger of
Dombrov. He is the younger son-in-law of
Naftali Zvi Halberstam, the fourth Bobover Rebbe. Following the death of his father-in-law right before the
Purim holiday in 2005, a dispute arose as to who should be the
Grand Rebbe of the then 120,000
Bobov Hasidim worldwide. While the majority began to follow
Ben Zion Aryeh Leibish Halberstam, his father-in-law's half-brother, others followed the older (by one year) Unger, who had by then already ensconced himself firmly within the community. Unger could not challenge his own father for leadership of Dombrov, which anyway was not as substantial a dynasty as Bobov. The matter of succession was brought before a
beth din (religious court) in 2007, which ruled that Halberstam would be declared Rebbe of Bobov () with its headquarters on 48th Street in
Borough Park, Brooklyn, while Unger would be Rebbe of
Bobov-45 (), located on 49th Street. ==Rebbes of Bobov==