So there is a certain “Royal Treasure” hidden away somewhere in Mariejois which the World Government, or more accurately the Tenryuubito, would do anything to keep from being found out by the world. For that reason once Doflamingo had come to find out about the existence of such a “treasure”, the Tenryuubito used everything they could to try and kill Doflamingo. But with Doflamingo being too strong and able for them, they opted to cooperate with him instead, hence why even with Doflamingo attempting to destroy everything the Tenryuubito controls around the world, they still ended up giving him a hand when he needed it earlier in this Dressrosa Arc. In addition, Doflamingo intends to use that “Royal Treasure” to obtain the “treasure” of this world, but for that he needs Law’s Ope Ope no Mi.
Looks like more than a few Sternritter arrived in Reioukyuu (Soul King Palace) than just Yhwach, Haschwalth, Uryuu and those fodder that were defeated earlier by Tenjirou. For another named Sternritter to be present at the scene, how exciting and what a curious ability he has, to be able to bend attacks of others. If he is here, I wonder if anymore Sternritter will make an appearance in Reioukyuu, as there are still several unassigned Sternritter letters. Anyway with Ichigo and Co. heading to Reioukyuu, I wonder how they plan to face Yhwach and handle Uryuu, who is obviously in a tough situation.