Most of the names below were found on the Fandom Wiki, because I am too lazy to go through the entire series a third time. And not all names are here are for certain going to become a new member of Yang Kai's Harem... Yet
Total potential missed Harem Members : 65
Number of potential wives/concubines : 63
Number of potential wet nurses : 2
(Note: in this case, wet nurse count above are the number that actually go through the ceremony as if they are a concubine. But hold a position closer to that of a caretaker instead of a lover, but will still bear children with Yang Kai. This is unlike what the other inevitable wet nurses would be.)
Starting World
-Hu Mei'er
-Hu Jiao'er
-Qiu Yi Meng
-Luo Xiao Man
-Bi Luo
-Lan Chu Die
-Zi Mo
-Leng Shan
-Han Xiao Qi (from Then Thousand Flower Palace)
-Ye Han (from Then Thousand Flower Palace)
-Hua Ruo Ling (from Then Thousand Flower Palace)
-Liu Qing Ru (from Then Thousand Flower Palace)
-Ye Qingsi (from Asura Sect)
-Yun Li (From Shang Qing Luo's Fragrance City Palace)
~Wet Nurses~
--Ruo Yu
--Ruo Qing
Tong Xuan Realm
-An Ling'er
-Mi Na
-Cai Die
-Ruan Xin Yu
-Shui Ling
-Guan'er
-Han Fei
-Ji Meng
-Li Rong
-Yun Xuan
Heng Luo Star Field
-Bi Ya
-Chen Shi Tao
-Qian Mo (probably)
-Dai Yuan
-Wu Yi
-He Miao
-He Zao
-Lu Ying
-Luo Lan (Possibly)
Star Boundary
-Bian Yu Qing
-Chen Bing Ru
-Chen Qian
-Chi Lian
-Lan He
-Lan Xun
-Li Shi Qing
-Ling Yin Qin
-Du Mi'er
-Ma Yin
-Mo Xiao Qi
-Fan Xin
-Fu Ling
-Qin Pei
-Hu Fei
-Hua Qing Si
-Yang Yan
-Zhang Ruo Xi
Outer Universe
-Ah Sun
-Lan You Ruo
-Lu Xue
-Luo Hai Yi
-Luan Bai Feng
-Die You
-Mo Mei
-Mu Qian Xuan
-Gu Pan
Ink Battlefield
-Bai Yi
-Feng Ying
-Smiles