do you mind if i ask if it's a good idea to let a vassal have more than one duchy? seems dangerous if they join a faction but i already have too many people to please!

omfg and now my brother has formed a faction against me

Yes it's dangerous I did it once with one who was really competent and loyal and it did end up badly (I mean I won but he did rebel) No son you could give this to? I like to keep revoked titles in the family as much as possible (yes I am a mad dynast!)