Shield | Invite user

Hi,
I'm creating app using "Shield Auth" library and I don't want users to register but be invited by the admin. So the flow I need is 

1. admin trigger a email to the user (shield create user with only email and no password on DB)
   
2. user get a link that get verified by shield when clicked
   
3. valid users are prompted to setup a password (with out old-password).
   

Can someone help me with these steps. I want to rely only on shield features and create custom functions only if needed so that I can keep using Shield with future updates with almost no code updates.