Complex sentence: Rabbi Chaim Yashua Halberstam was declared by the Satmar leaders in Monsey NY as the successor of the Satmar congregation in Monsey NY, unlike the two sons he's not considered as a global leader but rather limited to a local rabbi in Monsey.
Split into simpler sentences: Rabbi Chaim Yashua Halberstam was declared by the Satmar leaders in Monsey NY as the successor of the Satmar congregation in Monsey NY. Unlike the two Teitelbaum sons, Halberstam is not considered as a global leader; his status is limited to that of a local rabbi in Monsey.