We are trying to create a preference center that is somewhat dynamic.  We would like anybody to be able to subscribe to certain lists but not others.  For example, we have an Ohana Club list.  This provides special offers only to qualified individuals, so we want those who are already signed up to Ohana Club (and have confirmed their eligibility) to be able to unsubscribe, but we don't want those who are not members of that list to be able to add themselves to that list.  Is there a way to create the preference center so that only those who are already subscribed to a specific list will be able to see that list in their preference center?