The Guides don't mention anything about forced diplomacy. That was only discussed in this thread https://www.twcenter.net/forums/show...1#post16150489
And the person that opened the thread was asking about forced diplomacy so i explained to him how it works. Only then did i realise that he was playing the old campaign so i explained to him
Not sure where he got the idea that forced diplomacy was in 1345. All of our announcements show it as a feature for the 1448 campaign