role var reference group_var

Hi I was wondering if there is a way to have a role var defined under
defaults to reference a group_var. Basically i would like one file to
change if specifics need to be defined per deployment/site. Here is a
quick diagram to perhaps explain it better:

group_vars
    all <--- master vars
roles/
    common/
        defaults/
            main.yml <-- sub vars referecing master vars

Can this be done?