I know you can set the alliance to invite or set restrictions ( which is a great addition) but it would also be nice to be able to block players from joining. Hoppers that come and go repeatedly can be annoying. Some come in for a while and then want to stir the pot some then leave.
For a list of various reasons, It would be nice to have the ability to say someone can not join. Maybe add a check mark next to the Kick button too.