I rarely do these idea-threads since they never get implemented anyway, but it just occurred to me that if several parties are involved in a war, there should be more complex diplomatic screens with all parties involved. It would, among other things, solve the "my enemy surrendered to my much weaker ally" problem. I'm not entirely sure if this could be properly realized at all, but I'm envisaging something like repeatedly choosing what everybody offers to everybody, and unless everybody accepts, no peace is made. The aforementioned "surrendering to the wrong one" should still happen, though, if two parties strike a "ok, you surrender to me and I turn on my ally" deal. As a sidenote, it would also be cool to be able to trade vassals. Handing over the sovereignty of vassal states was common in history, after all. I understand that the idea behind being unable to release vassals gained in war is that it is supposed to be a choice one should undertake very carefully, but giving up a vassal for peace could be an exception.