Multiple Chromecasts - no choice selection

I have multiple Chromecasts in my house (4 - living room, my wife and I, our two kids' rooms) and VLC for iOS only has a button that plays on a Chromecast. Generally if I'm home alone (I work from home) it plays on the one I'm using. However, if anyone else is using one, it seems to pick a random one rather than let me choose (I'm sure there's some logic, alphabetically first or something - but from a user point of view it feels arbitrary).