Yes, I would perform a factory reset on all Sonos devices and let the new owner set up the system from scratch using their own Sonos account.

great thanks for your quick reply!

The Factory Reset will destroy all of your music service registrations, SONOS Playlists, and such. If you want to preserve these, temporarily add a Factory Reset unit from the new house to the old house. You can then use this unit as the base unit at the new house. At the new house add other Factory Reset units to this base unit. You can also do the inverse. Factory reset all but one unit from the current house and take this unit to the new house, build your new system by adding to this unit, then Factory Reset the shuttle unit and send it back to the old house.

You could offer to set your old gear up for the new owner if they seem nice.

Ulterior motive, once set up it will come off your Sonos account.

Thanks so much for the replies - will use Buzz’s advice and copy off an existing unit and propagate to the new sonos units - just saved me a lot of anguish with the family!