Sir Laurence Olivier famously left Rosencrantz and Guildenstern out of his Hamlet. So, play director for a minute. Who else appears to be a major character that you think you could get away with cutting? You are allowed to give that character's lines to other characters, as necessary, but you can't invent new characters to compensate. No merging to create a new and unique character (so no blending of Tybalt/Paris/Prince into a single entity ala Sealed With A Kiss).