Mijia and Zhui app cannot be added at the same time.

I can't. Mijia is a smart home brand owned by Xiaomi, which was released by Lei Jun, the founder of Xiaomi Company, in Beijing on March 29th, 20 16. Xunmi Technology (hereinafter referred to as Xunmi) is a brand of Xunmi Technology (Suzhou) Co., Ltd., and Yu Hao is the founder. They are not the same brand, so they cannot be added at the same time.