I pulled this out into its own support topic so we can focus on it. This feels a little complicated. Maybe we can try to address your problem by breaking down what it is you are trying to achieve.
If I understand correctly, you have an invite only community and would like to allow your members to invite more people to join and get credit for inviting people, but you want to be able to control what groups invited members are added to and what topic they land on first. Is that about right?