In order to get a PU, you have a very little chance to get a message telling you that a PU was formed with the other country when you only have a royal marriage. The best way is to Claim Throne (diplomacy option), that is only active when the other country has a low legitimacy heir IIRC. That would give you a Casus Belli on them so if you reach 84% warscore, you can force the PU with them. You could also be lucky to simply claim the throne and get the PU created, but I think the chances are low anyway. The other option to force PU's waging war is to use a spy, clicking on the capital province of the country if said country has legitimacy under 50%, so that would give you a CB worth ~94% to force a PU. After you win the war, make sure you improve the relations over 0 or you will lose the PU if your monarch dies! :laugh: