Dorgon was Nurhaci's most beloved son in his later years, and from many historical records and Nurhaci's instructions to the lord of the Eight Banners during his lifetime (he personally led the two yellow flags, the positive yellow flag, to Dordor, and the yellow flag to Azig). No clear arrangements were made for Dorgon, who was in the middle of his age and most beloved, and shortly before Nurhaci's death, dudu, the owner of the white flag, was transferred to the red flag, presumably to give the white flag to Dorgon), indicating that Nurhaci was interested in Dorgon inheriting his Khanship. However, at the time of Nurhaci's death, dorgon's three brothers were still relatively young and far from being able to compete with the four great belles. Therefore, Emperor Taiji was able to inherit the Khanship of the Later Jin Dynasty.
After the death of Emperor Taiji, Dorgon and Hauge competed for the throne. Although Dorgon's exploits were the greatest, the supporters and appeals were also the greatest. However, under the strong demands of the two yellow banner generals, who were directly subordinate to the Emperor Taiji, they fought to the death and became the crown prince. Dorgon also had to compromise and retreat to the throne, with Emperor Taiji's ninth son, Fu Lin, on the throne, and Zilharan assisting him. Although Dorgon was in power, he once again passed by the throne.
If it is said that after the death of Emperor Taiji, the conditions for Dorgon to be called emperor were not yet ripe. Then, after the Manchu Qing Entering the Pass, Dorgon's power was already unstoppable, so why did Dorgon never usurp the throne and become emperor?
In fact, a large part of the reason is related to the childlessness of Dorgon, who has only one daughter, although he has a large number of wives and concubines. Hauge once scolded Dorgon as a person who was "sick and unblessed", and then judged from the fact that Dorgon su suffered from wind disease and died suddenly in his prime. Dorgon should indeed suffer from chronic diseases that make his fertility extremely low.
After the Manchu Qing Entered the Pass, Dorgon was already the emperor in fact, and the usurpation of the throne as emperor was nothing more than a false name. However, he has been childless. The best case scenario is to have a son from his own brother, and then to the throne after his death. But this stepchild is not much closer in blood relations than his relationship with Shunzhi. So, why risk infamy to toss it? After the death of Emperor Taiji, Dorgon was still active in fighting for the throne, and should be relatively young at that time, and he had great expectations for him to have children.
However, after the Manchu Qing entered the customs, Dorgon never had a parent born. Although his power is also unstoppable, no one can stop him from becoming emperor, but without his own son, he will lose the motivation to become emperor. Judging from the fact that Dorgon gave himself the title of "Emperor Father Regent", it was obvious that he wanted to directly change Shunzhi to his heir.