What word should be added after the word catalpa in the middle of the name?

Girls: Zi Qi, Zi Xuan, Zi Xuan, Zi Tong, Chen Zi, Zi Qian, Zi Ruo, Zi Nuo, Wei Zi, Zi Yue, Zi Xi, Angel, Zi Shu, Lin Zi, Zi Xue, Zi Meng, Zi Meng, Zi Qiong, Zi Huan, Zi Li, Zi Qun and Zi Nan.

Boys: Zi Hao, Zi Hao, Chen Zi, Lin Zi, Zi Jun, Zi Peng, Yu Zi, Tian Zi, Zi Feng, Zi Long, Zi Jie, Zi Jun, Zi Jiang, Zi Rui, Zi Yi, Zi Xi, Zi Hong, Zi Ya, Wei Zi, Yu Zi, Zi Zhen, Zi Quan and Zi Xi.