The screams of the elder duo died rather quickly around the same time as the other two had, it didn't take much time for Yun Jhin to enter their souls and make them subservient to him, it wasn't mind-control but more of a mind washing technique, Yun Jhin couldn't control God Realm experts or above but he could change their thinking somewhat which wasn't as sure-proof as complete control, they still had their own thoughts and they could control their actions but they would mostly do things that were beneficial to him.
It was something akin to a cult or hive-mind mentality, however that meant that if they found Yun Jhin to be a bad leader or weak leader there was a high chance they would revolt.
Yun Jhin left the two elders alone to continue their job and returned to sit on his bone throne as he thought a little bit about the current situation of the sect.