Add a new group into UserGrp named "Visitor"   CHIT
Add foreign key to WebpageContent and change all allowed_grp to visitor    CHIT
Add parent to UserGrp (As I mention yesterday, the super group and child groups concept)   CHIT
Add permission(grp_id) to AlbumPhoto(optional) & Album   OK
grp_id in UserGrp should be singular (e.g. Staffs -> Staff)  OK
Change event_date in Album to event_id and set as foreign key  OK

                User
                 -------------------------------
                 ▼                            ▼
              Visitor                    Visitor only
                 ▼
               Member        Staff          Admin