Also, in a future EU game the union mechanic could be modified to be more fluid. After listening to the Russian History podcast I realized that the Commonwealth was at the beginning lead on the international stage by Lituania's interests, and it is logical as Lituania's duke was offered the crown of Poland and he still was viewing internatonal politics from the point view of Lithuania's intersts first. So, there could be a mechanic where Lituania by event will get Poland under personal union and on the death of the monarch an event will pop up that will offer you to switch the senior partner of the union. This event and mechanic should be not only specific to Poland-Lituania. For example if a smaller country inherits the throne of a bigger one on the crowning of a new monarch the player has to make a choice and if he picks to leave the smaller country as the leader of the union then the PU partner will have a penalty to their Liberty Desire. In to that Liberty Desire penalty should factor the stated dev and heavily factor in the rank of the country. For example an emperor will have enough gravitas just from the sheer prestige of his title to hold even a somewhat bigger than his realm duchy. A penalty to Liberty Desire could be added to the country from which you switch with a cooldown for it to decrease.