What are the things which affect diplo-annex? I'm playing Ottomans and got into a nice alliance with Crimea, helped them grow a lot and they loved me, so I decided I wanted to diplo-annex them. I put quite a bit of effort into getting them above 190 relation, getting a royal marriage etc... and then I get shot down immediately when I see that they get a -1000 chance to accept vassalisation since they have more than 3 provinces. Can you get rid of this block, or is there something you can do to get +1000 chance? Because honestly, this just seems like a downright rule (you can't ever vassilize a country with more than 3 provinces), which I would have liked to know before I invested in getting them to that point...
This is the problem with EU games having such terrible manuals, none of this is covered.