DarkRP Citizen whitelisting/blacklisting

Hi guys,

The server I've been working on is serious RP so we've designed it so that when you change to a certain job you can't just leave your position. I.e If i decide to be a policeman I can't just open the menu and change to be a gangster.

This is set up perfectly find but the only issue I have is that the user can still move back to the default 'Citizen' role, and I can't amend the black list for this using billy's whitelist. Wouldn't be too much of an issue but it means people can quit their jobs and pick another - which we don't want

Is there any suggestions people can make to stop players being able to swap back to citizen?