I always wondered why on TNG they used Denise Crosby several times, including made her reprise her role for the series finale in spite of killing her character off very soon in the series, while they completely erased Terry Farrell from the show to the point of absurdity. I mean, how believable is it that Worf of all people would flash on his stay on DS9 and not have a single thought for his wife? Not very!
This was another negotiation that broke down. It's not clear what happened, but Terry Farrell claims that she wanted to act in the finale in some manner.
However, there were 7th season flashbacks to Jadzia Dax: Ezri has them when she breaks into Worf's quarters at the beginning of the long arc. We hear Jadzia speaking to Worf, recalling key moments in the previous seasons. Moreover, her image is present in the wedding photograph.
Wasn't there also reports that Farrell wasn't happy that clips from previous episodes had been used without her consent?
So even if she had wanted to act in the finalé she might have not endeared herself to the producers with past actions.
Hard to say. Clearly her relationship with the show was rocky. She only ever talks about having good relations with Brooks and Dorn, and she references the exasperation everyone had with her poor skills in broad terms. I can't remember ISB or RB saying anything about her in recent interviews, particularly with regard to the late seasons. Maybe there's something burried in a Larry Nemicek talk.