https://tvline.com/2021/09/02/greys-anatomy-kate-walsh-returning-season-18-addison/

Walsh will reprise her Dr. Addison Forbes Montgomery role in multiple episodes next season. Details of her return being kept under wraps. Walsh last appeared on Grey's Anatomy in 2012 and starred in the 2007-2013 spinoff Private Practice.

I DO like her, so great!!!!!

Grey's Anatomy teases Kate Walsh's return (https://www.primetimer.com/item/Greys-Anatomy-teases-Kate-Walshs-return-JWSnzv)

Check out a preview of Dr. Addison Montgomery gracing the halls of Grey Sloan once again starting in next week's episode.

"Grey's Anatomy" Alum Kate Walsh Sets Next Return Date
by Charlie Mason
April 6, 2022


TVLine can report exclusively that Kate Walsh will appear on "Grey's Anatomy" for the Thursday, May 5th episode.

Walsh first announced her casting via TikTok:
https://www.tiktok.com/@katewalsh/video/7083535707159104814?is_copy_url=1&is_from_webapp=v1&lang=en

https://tvline.com/2022/04/06/greys-anatomy-kate-walsh-return-date-addison-montgomery/