Conditional toggling of 'nullable'

I am trying to setup a registration form using breeze where somebody can create an account using an email and password and they can fill the other profile details like first name, last name , phone-no afterwards ie; they are set to nullable . I would like to have a checkbox asking those registering something like " Are you a medical practitioner ?" and if the click it would like to show a form where they 'should' fill first name, last name and phone-no for completion of registration . How this can be achieved in laravel ? Should i use separate tables or roles ? Any help would be appreciated and thanks in advance .