How to confederate Cathay?

Playing juan bo, turn 80, I have the norther and western LL lords and I cannot confederate them, I even have yaow ming at 400 after giving her an entire territory, and confederation is still at -52..... Im strength rank 7, shes 14. I assume she just needs her entire armies obliterated or something? Which will never happen because everyones super friendly. Does anyone know a way to do it, ive already give 4 settlements to boost it to +400