I don't know if anything similar has been posted before, so, sorry if it has!
Season 8 was the last season all of the core cast were contracted for. Yet, it felt like a filler season and they brought back no fan favourites (despite it likely being the final season).
They crammed so much in season nine and rushed through it, I think some of it could have happened in season eight.
Brooke's wedding was the perfect opportunity to bring Ted into her life. And possibly others, Deb & Karen. Brooke went to Deb for help after being attacked. And Karen was basically Brooke's mother during her teens. Even if Hilarie didn't want to return, I think Karen and Deb had just as much right to be there.