I'm creating a new 'premium' user group. I'd like to copy the 'registered' user group permissions and then add new permissions for the premium group. Is it possible to copy/clone existing group's permissions and then simply modify them for the new group? Thanks.
The way permissions work in XenForo that wouldn't be the ideal way of doing it. Your Premium group should already inherit the registered group permissions, everyone should have registered set as their primary group even admins. You just need to set the extra permissions that you want the Premium group to have.