php - how to allow multiple or sub accounts in codeigniter using ion auth

i have created a website which allows user to register and pay subscriptions. I have 3 user groups, comprising of admins, editors and common members. i want when a member joins, they can be able to add child-accounts to their account which will get all the benefits their parent account. My tables are currently the generic ion auth tables with a little tweaks to match my requirement when joining and login in. Please help me with how best i can achieve this. perhaps the the workflow:

My current worklow follows this pattern:

select package>fill up the registration form>confirm selected package or change>make payment> but user cannot create child accounts.