Problem with war declaration

[Zuru84]

When I am trying to declare a war to Slavic country Yatvagi I have two options: Holy War of Lietuva and Holy war of Zemaitija - but those are two separate countries. Is it a bug? Why I can't declare war to Yatvagi when clicking on their main Liege but I have options connected to other two Kingdoms?
I also noticed that this issue is also connected to other countries (checked on few slavic countries).
Screenshot attached.

 

[vukica]

Unless you're a religious head you can only declare wars for de jure duchies.

If the target character holds only one county in a duchy, and you declare HW for that duchy you only get that one county. To get the duchy you must either attack whoever holds the duchy title, or get 51% of counties yourself and usurp/create.

I hope that makes sense.

 

[Zuru84]

It makes perfect sense. Thank you!