Ye Xiao and Great Star Lord returned to the Great Star Palace. After meeting with the other Star Lords, Ye Xiao went straight to the Eight Star Palace. After putting on the mask, he became the Eight Star Lord.
As for some of the Star Envoys and members of the Eight Star Palace, the trusted aides of the previous Eight Star Lord, all of them had been informed of the whole story.
Just like that, Ye Xiao replaced the previous Eighth Star Lord and stayed in the Star Palace. When the previous Eighth Star Lord will be completely healed and come back, Ye Xiao will give back the position of Eighth Star Lord to him and leave the Star Domain. This was the condition he put forth before becoming the Eighth Star Lord.