Disney released details on a new Frozen Holiday Premium Package at the Studios, which includes reserved viewing for the Osborne Lights and a dessert party, in addition to reserved seating at your choice of Frozen Sing-Along: https://disneyworld.disney.go.com/dining/hollywood-studios/frozen-holiday-premium-package/.
At Magic Kingdom, Anna and Elsa take over for Cinderella at the Castle lighting ceremony, scheduled nightly at 6:15pm beginning November 5th. It should continue through January 4th (end date not confirmed).
In unrelated news, the new Haunted Mansion store that replaces Yankee Trader near the attraction is expected to open officially October 6th. A “soft opening” is expected later today.