Po Di and Chi Xue were clever. Though they never explicitly asked Young Master Joyful and the others to remain in the alliance, they used other means to tempt or threaten them. For instance, they dangled Saint-grade Heavenly Treasures such as the Phoenix Soul Fruit and the Ginseng Fruit Tree before them. After all, apart from the Po Family Brothers, Chi Xue, and the other God Devouring Bodies, Young Master Joyful and the others had not obtained any Phoenix Soul Fruits. And there was only one Ginseng Fruit Tree. Although it provided less and less life force as time went on, staying with it was still far better than the situation most cultivators faced.
Of course, faced with danger, these temptations were no more than bubbles, so Chi Xue and the others also resorted to threats. They pointed out, for example, that cultivators from the God Realm's major alliance of powers would eventually attack them, and that the Divine Beast Alliance would seek revenge. This further convinced Young Master Joyful and the others to remain in the alliance.
It made sense. The forces led by Young Master Joyful and the others had killed many cultivators from the God Realm's major alliance of powers, and their feud with the Divine Beast Alliance ran as deep as the sea. If they left the alliance, they would surely become targets of these forces' revenge. They had no confidence they could survive being targeted by them, so staying in the alliance was the safer choice. What was more, Chi Xue and the others had already come up with a way to deal with the threat: destroy the Teleportation Formations they had previously set up throughout the God Realm and build new ones. These would be enough to hold off Venerable Sword Saint's surprise attacks,