Hi Qie, I appreciate you spending time to reply so let me clarify a couple of points. When I talked about the group membership I was referring to the settings of the security system, where you can set the allowed users to a group only. In fact it doesn't check group membership but active tag, you are right. So I am happy to have people wear the group tag always and therefore check they are members of the group.
You are also right about the ejection destination. I am not able to teleport them were I want. But either eject them or tp them to their home. I still haven't been able to find a solution to this. But my primary focus was being able to control that only members of the group can stay on the land. So its certainly not ideal, but gets the job done for now.
Thank you for your suggestions.