[Q]

Originally posted by Imperator Fyron:
Treaties only give you a one time happiness bonus. You do not get -100 anger per turn when you have a Partnership; you just get that bonus when the treaty is signed.

That's exactely what we are talking about.
As far as I know a treaty is signed and gives you the change in happiness even if you had a different treaty before. And that seems to be true even if the old treaty was a higher one.