Voice command to stop one HomePod when streaming to multi-rooms

Most days we stream BBC Radio over 2 or 3 HomePod Minis from one device, which works well enough (native BBC support for HomePod is a well trodden path I don't want to go down again here). However, when a scheduled program comes on that I'm not so keen on, I've tried all sorts of commands to break just one HomePod from the multi-room stream but it always takes all them with it. This invariably leads to my wife starting up the radio again from a different device, which also stays multi-room even though she doesn't explicitly choose to do that. So I end up cycling the power on the HomePod local to me, which is not ideal.

Clearly I know I can go to the device they are all streaming from and take it off from there, but that is almost never in the room I want to change the music in.

Does anyone know any Siri commands to get around this, that will just disconnect the local HomePod from the group?