Help Premium account adding family member who already has a free account

[julia1965]

We have a new premium account in my oldest son's name.  My younger son had the free account but Im trying to add him to the premium family account.  I fill out his name/email/etc and get a email invite.  When I hit the accept invite, I get a message that says      "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". 

I don't understand what the problem is.  

I want to add his existing free account and keep his music and get him onto our new premium account  Thanks in advance for your help.

[Maxim]

Hey @julia1965,

I'd recommend making sure that the correct account is logged into the Spotify website when trying to accept the invite 🙂