One of the criticisms plaguing the Arrowverse’s Invasion! event last year was the minimal, nearly non-existent, involvement of Supergirl. While Kara herself remained a highlight during the three episode-arc, her show acted as only a tangential lead into The Flash officially kicking the crossover off. Apparently, this will be rectified to some extent for what is planned the next time around.
According to Stephen Amell (via Screen Rant), an effort is being made to get everyone more involved:
“I think the idea this year, from what I understand is, last year they said four-night crossover but in a lot of ways, Supergirl was just kind of a lead in to The Flash, so I think this year they really want to get everyone involved. It’s not going to be a four-night, well I guess four-night, but Legends and Flash are on the same night. I think they want to get everyone involved in every show. I like having the anchor, we have the anchor this year, Thursday night.”