Yeah, developing rapport takes time. I think at this point focusing on developing on-going rapport is the way to go. They are currently resistant to change, so you've to earn their respect and trust before they can accept anything new.

One way to do it is letting your consumers run the group. Let them talk about how they feel about structured weekends, have them set up rules in the group while you still retain some control in the group by letting them know that setting rules up for XYZ reasons and these reasons are solely for the benefits of their well being (basically create a reason that can be shared by everyone in the group and have them believed in the significance of having rules). And if they don't want rules then have them talk about what's it like to have/not have rules, and during which you can validate their feelings and just let them know that you are here to listen.