Hey guys I had a question: If my ruler dies when I have a PU, does the PU go away or does it keep going? I just wanted to kno seeing I am Holland and I have England and France as vassals, I want to integrate them into my Empire! 
Personal unions will continue when mutual relations are above 0 (or is it 100?) And a chance of inheritance will occur when your king dies.
Now, when you say that England and France are your vassals, do you mean they are in a personal union with you, or did you subjugate them? There is a distinction between the two.