In addition to the subject line, this text appears:

"Sorry! You're already a member of this (or another) Family plan. Please click below to switch to the account that you want to join to the Family plan."

Then you are supposed to click the green button with this text:

"SWITCH ACCOUNTS"

When you click switch accounts a nw logon screen appears. No explanation at all. It all disappears in thin air.

I have added my two children successfully. My wife has ended her Premium account, but gets the above cannot join message repeatedly. Don't understand the way out of this. Spotify close to losing a customer. Any help appreciated.