I've just realised that despite what I had previously thought, all of my devices connected over Thread are using my Google Streamer as a border router instead of the HA one available from my Yellow via OTBR.
Is there a simple (or even possible) way to move my devices over, or at least add new devices to my HA Thread network? My Android phone refuses to use any Thread network other than the Google one when adding new devices, even when it isn't actually available. I can't find any way to change this - it will always try and put it on the Google network rather than the HA one no matter what.
I don't want to rely on a separate Google border router when I already have one built in that is available but I just seemingly cannot actually use.