Currently, Spotify Family only supports up to four subaccounts in addition to the administrator account. So in you case you would need three different administrator accounts, which would mean that three family members would be paying full price. The total price would be $89.97 ($29.99 x 3), not including taxes.
Follow these steps here to sign up for the Spotify Family plan and invite your family members. Remember, you need to repeat the process three times since a Family Plan can only have four subaccounts.
If you run into any issues or have any other questions, let me know! 🙂
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