Has diplomacy changed in Nov 26?

[unmerged(20844)]

I'm currently playing as Burgundy and the situation is, I force-vassalized Genoa while they were allied with Venice, Siena and a bunch of other minors. Then i was preparing to diplo annex them when i noticed it was impossible to invite them to my alliance, because they were already in one (and still were my vassals)! This time it was a different allience- with Castille, Eire and the Pope... Meaning, that they must have gotten into it AFTER I vassalized them! Otherwise they would automatically have left it as a result of the vassalization!
It's the first time i see this, could it be a Nov 26 bug?
(the game is in the AGC, which has never made a single problem for my pc) I can post a screenie if someone tells me a site i can upload it on, the one i used is down until November 30th

 

[ForzaA]

i *think* it may have been a scripted alliance (ie. they got an event that gave them an alliance with one of the other members )

 

[unmerged(20844)]

ouch, never heard of these scripted alliances. Shouldnt such an event first check if the nation is independent?

 

[AndrewT]

Ideally, yes.

 

[unmerged(19088)]

It could be the "Holy League" or the anti-Venetian "League of Cambrai"...