Hello,
If you're setting up different membership plans and letting people sign up for whichever one they want, it's a good idea for members to sign up for the ones that are available. That way, they can refer other people to any plan and build their own member structure. Otherwise, members might only get commission from their new referrals, but they might not be part of their own member structure if their referrals sign up for a plan that the member hasn't registered for yet.
Regards,