Add registration to backend login

I want to add a registration form to the login on the backend but I cannot seem to find anything decent.

I find lots of stuff to redirect and create your own login and registration forms on the fronted as a page for example, but they all conflict with a directory plugin I'm using. Basically the plugin pushes to the standard login page every time, so the easiest thing is just to modify that one.

Any suggestions? Tnx