Hmm I can't answer your comment. Anyway problem is that if you look at the code in invites.bml there's no hardcoding of those strings it fetches the variable part from elsewhere (sorry for my lack of technical terms!):
        foreach (@allattribs) {
            push @tags, $ML{".label.$_"} if $args->{$_};
        }

I could switch it to label2 but then I'd have to edit all the strings (not a pb). What do you think?