There must be a way of just putting a link on a page to the register box?
You can make them super users and simply login to the back end. I’m unaware of any plugin that will allow such things from the frontend.
You know how a non-user can normally register themselves is there not a way of adding this link to page – what I’ve done is create a page called register user and I’ve used a plugin to hide this page unless the person using the site is logged in. Now all I need to do is create a link on the register page to the register form (that is normally accessible for a non-user to click on). This way only registered users can register non-users if that makes sense?
Maybe its not possible because there is already a user logged in and I’m asking WP to do something that it wasn’t designed to do
Well by understand how the register works you could make your own PHP form that injects the user into the database without even WordPress. Not hard stuff but I recommend you checkout Stack Overflow on how to use forms and pass information into the database.