Broadcast and convergecast are two fundamental operations in wireless sensor networks. Although previous works have addressed energy-efficient and low-latency scheduling, these works either consider only one-way (broadcast or convergecast) communication or are not compliant to ZigBee/IEEE 802.15.4 standards. Motivated by these observations, this work defines a two-way beacon scheduling problem for ZigBee tree-based networks. We propose a scheduling algorithm that can reduce indirect interference neighbors and achieve low-latency broadcast and convergecast. Simulation results are presented.