Apple TV 3rd Generation With HomePod mini Stereo Pair

I am using an 3rd generation Apple TV with a HomePod mini. While I have a stereo pair this Apple TV sadly only streams to one of the HomePod minis. I believe this is a software issue rather than a hardware one. World it be possible to add that functionality as I would consider throwning out an otherwise perfectly suitable Apple TV an unsustainable move? I hope I could made that point clear enough and you can easily fill in….. Thanks for your consideration.