After sending an invite to another Spotify user and them accepting the invitation to the Premium Family plan, the only information available to the plan manager regarding the added plan member is their username (not their email address). Feel free to also check the answer to this similar thread.
When inviting another Spotify user to the Premium Family plan, the plan manager can either choose to send them a link, or invite them by entering their email address. You can read about how the plan manager can invite other members in the answer to this Q&A thread; and for more information regarding the Premium Family plan, you can read this support article.
I hope this helps, and let me know if you have any other questions.
Have a good day!
TreyAnastasioRock Star 6
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