The Empire had a princess named Ina.
Ina was not the child of Higuain and Tang Ling. As a powerful Space God, Tang Ling's age was actually much older than Higuain's. Moreover, with her elementalization, she was long incapable of bearing children. It was under Tang Ling's special permission that Higuain had Ina with a maid. But after giving birth, the maid was killed by Tang Ling. Ina later, because of her outstanding magic, was reluctantly taken in as a disciple and stayed by her side. For the benefit of the country, she even went so far as to sow the seeds of affection. And Higuain had no right to stop any of this.
The reason for allowing Higuain to have Ina was for the future, so there could be someone to inherit the throne and continue to be the puppet of the Tower of Gods.