Wendy's writing a couple of mysteries, with characters that she has to focus on, and stuff happening simultaneously. In The Avengers they handle it well by showing us what Iron Man's thinking or doing, then hopping over to what's going on with Captain America, or the Hulk. The transitions are smooth, and we're tracking parallel timelines.
I brought up the case of Chariots of Fire, too, where we see Harold Abrahams and his reasons for running, then leap to Eric Liddell and his motives. Parallel timelines. I think that if you hop back and forth, and don't stay too long on each character, we won't forget about the other ones. Case where they dwell on one too long (or not enough) is, and I hate to rag on it again, Batman v Superman: Dawn of Justice. We spend nearly the first third of the movie on Batman, which is great, but Superman gets just some tips of the hat, leaving Wonder Woman with a small slice at the end.
For more of my meanderings on the movie/writing subject, check out these posts: http://writefromthegitgo.blogspot.com/2016/04/words-like-fire.html
Hope some of this made sense. I just had this embedded in me, like a splinter, and had to yank it out.
Okay, I've yapped enough. Stop reading me and go write.
Keep writing, friends.