The prince is not the eldest son, he can also be other sons! The sons are collectively called princes and are divided into the eldest prince, second prince, third prince, etc. In the Qing Dynasty, they called elder brother, not prince!
The emperor's mother is called the Queen Mother, his daughter-in-law is called the Queen or the Concubine, his grandmother is called the Queen Mother, his father is called the Supreme Emperor, his sister is called the Princess; his brother and younger brother are called Emperor Brother, and his uncle is called Princess. He is called the Emperor's Uncle, and the husband of his sister is called the Prince Consort. People often say: Your Majesty, Your Majesty, Your Majesty, and Long Live Lord all refer to the Emperor! The Emperor calls himself: I am a widower and a solitary family member!