Check out this useful article by K.M. Weiland on managing the writing of large (and maybe even small) casts of characters. Here's a taste:
Rule #1: Characters Should Exist to Represent Theme and Move Plot (Preferably Both)Read the full article here.
The first and single most important principle to consider when evaluating the size of your cast is this: does each character matter to this story?
Characters, like any element in a well-thought-out story, should never be throwaway additions. Each must contribute to the story. Sometimes this contribution may necessarily be as small as a few catalytic or informational lines in a one-off scene. But the more screentime characters have, the greater your responsibility to make sure they contribute to the story on a larger scale.
It’s not enough for prominent characters to exist in the story merely to move the plot; they must also influence and comment upon the thematic argument, either symbolically or by directly impacting the protagonist’s personal arc of growth.
My thanks to K.M. for sharing, and to Cynthia Leitich Smith's indispensable Cynsations blog for the heads-up on this gem.
Illustrate and Write On,