On UX.SE, someone was given the advice to move a discussion to chat, and when he tried, he said this:
@charles if this site allowed the question "worst web interface" my answer would be the SE chat! Confusing interface, terminology, purpose... I create a room specify it is for the UX site, and after submission gets assigned to serverfault.
I went out to try this and created the following chat room: https://chat.stackexchange.com/rooms/961/test-ux-room
When I created it, I switched the Related Site to "User Experience" but it still got created as a SO chat room. It looks like it is not honoring what is selected on that screen for the related site.
Update - It looks like the chat rooms might just be using the site associated with the chat account being used to create the chat room.
Additionally - There are two "Stack Exchange Network" sites listed, currently.