Constantinople and foreign claims from 5 factions

[nightleaf]

There are 5 factions that have claims on Constantinople every save but they do not own any region on map.
They will abandon claim on Constantionple if you gift them 1 region but they accept all regions you want to get rid of.

templars
hospitallers
iberian order
sword brethren
teutonic knights

Are there some events with those 5 factions and Constantinople and what is point of their claims on Constantinople?

[Surt]

Byzant is heretic to these holy orders.

[Pocus]

They can very well get regions through military methods. I have seen saved games with the Templars with 50+ regions and large portions of the Holy Land.

[Surt]

You can hold them down, but it usually requires placing the Judean Liberation Army on permanent station in Judea.
As Byzant, Seljuqs and Fatimids its a doable job.
But you might want to either become friends with them or demand their claims in peace.