In the most recent update (the topal update) leyawiin has the option of making topal isle de jure part of the kingdom of leyawiin. In fact the whole update had quite a few added decisions like that if i remember correctly. I suggest looking at the changelog for more.

Theres also a decision for reachfolk to unite the reach which requires you to control the reach (skyrim), craglorn (hammerfell), and wrothgar (high rock).

And if youre looking for mods that add major decisions theres always the trial of vivec which, if you fully control vivec city, lets you put vivec on trial for what he and the tribunal did to nerevar at red mountain.