Assuming their playlists are stored in their Spotify accounts, why not just let them have their own Google Home with Spotify linked and their own Sonos account (with their Spotify service), each Sonos Household setup on the same local network, but with separate accounts. It just means their speakers will not play together, unless they perhaps choose to use Airplay2.

I don't think you can do this with voice control unless you set the speakers up as separate systems. If tbe speakers are used independently that may be acceptable.

It is possible to add multiple Spotify accounts to Sonos for control with the Spotify app. Have you added all three accounts?

It may just be possible to control Spotify directly on the phone using Google Assistant and then use Spotify Connect to play to Sonos.

I don't use Spotify or GA so I would not treat my answer as totally reliable!

GA uses the Spotify account connected with GA. As far as I know you can only link one Spotify account to Google.

Thanks, created now 2 accounts. The one thing which I dont like about is that we were able to set alarms for both kids in 1 account. Now you always have to switch accounts to change alarms if you don’t do it on the kids iphone.