One of my major responsibilities is creating a bi-monthly newsletter. I have to work with a copy editor who is holding onto projects for weeks and pushing us further behind on our deadline. I can't reprimand her because she is actually an administrative assistant for a different department who copy edits because she is good at it. She gets overly angry with any sort of comment about her performance. She is always right and never wrong. Now she is causing problems with the other office diva who's the graphic designer building the newsletter. He also has terrible time management and doesn't take constructive criticism.
How do I get my copy editor to return things on time?