Non-Admin User ability to send invite to new users

Request a system change to allow non-admin users to invite new users. Now, only the admin can send an invite. A new user's email address must be in the Users. I plan on selling access to the app in the future. I won't be able to monitor multiple app versions to add new user emails to the file before they can be invited to join. Create a way for non-admin Subscription purchasers, a restricted-admin User, to have the ability to send invites to their users, the way it works now for Admin, but the restricted admin User would not have the ability to modify the app or access app settings, and the dashboard or other selective admin functions