Is it possible to make a religious vassal mine?

[HybridRifter]

so I decided to play a game as Georgia. I also decided to become standard Orthodox. The Byzantines decided early on to go Iconoclast. I would like to validate version of the Orthodox faith by making the patriarchate my vassal and put an Orthodox pope on the seat. What are the possible ways to remove him as The Byzantines' vassal and making him my vassal when he only owns a barony? This question could also apply to any other religious head that has a title.

 

[Tryvenyal]

First of all, to have a King- tier vassal you need to be an emperer.

Secondary, I don't know if you need to be Byzantine/Roman to by decision institute the Patriach(if he does not exist) or if you "only" have to hold Constantinople...

But.. As Autocephalous Georgia, your religious head is whoever is you Court Chaplain, no matter who is patriarch of any of the 5 different Patriach seats.