I don’t use that type of family setup, personally speaking, but I think this maybe the way to go about it...
First, you setup family sharing (this is called an Amazon Household) via Amazon online or in the Alexa App (Settings/Account Settings/Amazon Hoysehold) and then first asked Alexa to switch to the chosen family profile added to the Sonos App…
Example: “Alexa, switch to Ken’s Profile” before then asking Alexa to play the saved personal playlist?
Hope that helps you to get it working.
Thanks Ken,
I did wonder whether separate household profiles might be required. I'll give it a go.
Cheers