Damn, adventuring with the Little Tiger, the monk and Yunzi would have been fun... how about a rollback...
If we just leave (A) then zhang becomes ruler of the Tufan, he does not like us but if he is Shun's man then this could be good for the Empire.
If we steal the princess (B) then we put her sister in a difficult spot. There are two ways I could see that going. She could decide to run away with Wuni like she is currently prepared to do or she may decide to stay. If all of her siblings are dead or missing she may not have it in her to just cut and run and leave her people in the lurch so to speak. If she stays then zhang becomes ruler and we have the same problems and benefits as in A only we now have another wife, a traveling companion or a hostage depending on how she reacts. It may not be wise to run to the Cult if we have her with us as we will likely be hunted and I do not know how well the Cult would respond to that sort of pressure.
If both princesses disappear I suspect the state will fall into turmoil in the short term. Their uncle, this Prince Lobsang, will probably press his claim if he is even remotely competent. The long term effect of this would be a larger and more powerful neighbour for Shun to have to deal with. Less than ideal to say the least.
A lot here hangs on whether or not zhang actually is in Shun's service. If he is then a puppet state on the border would be ideal while it would only be a danger if he is in league with anti-government forces. Sadly we do not really know enough to say one way or the other...
As a result C is the safest choice. If we accept the position we can get rid of zhang and ward off expansionist rulers like Lobsang. We would have to give up on a lot of what we want to achieve in the short to mid term...
On the issue of zhang, well he may still be Shun's man or he may be allied with the Eunuchs. Either way I don't see it as our problem anyway, leave him be I say.
Of course at the end of it all maybe it simply is not our problem to solve...
A2, this was a fun vacation but we really should get back to the task at had. Let the politicians
worry about politics and the Tibetans worry about Tibet, it is none of our business really.