@trucherrygirl FWIW from a film school Dad
Congrats on your acceptance at your 2nd choice school. I'd advise calling Chapman on Monday, so you provide them information and the longest time frame to choose/or not to provide you with additional information (or perhaps a decision).
I'd followup the call with an email summarizing what you had conveyed and what you had heard in the call with _______. Do not rely on that person, even with their best intentions, of conveying things accurately. If you had not already indicated it in your application, definitely indicate that Chapman is your first choice (and perhaps in one sentence why). You might want to reference an informal study that shows that grad students who attend their first choice school are more highly motivated, satisfied with the program, do better,and ultimately become ambassadors for the school. (Most of this I am making up from my very informal reading of forum posts and talking to professors etc.) Perhaps it doesn't hurt to champion your cause. While you will be "polite", being persuasive and perhaps even slightly pushy - well this side of being obnoxious - might demonstrate a motivated, can-do attitude that is usually a prereq for success in the field.
If you are accepted to Chapman, you are about to make a huge time and money investment, and while the school holds a lot of the power at this point in time there is probably little downside in championing your cause. While the official Dodge position is that they do not divulge decisions over the phone but rely on snail mail, there are obvious exceptions to this based on forum posts. In this digital age, reliance on snail mail is a bit retro.
If there is a particular screen writing prof that was important in making Chapman your first choice you might consider contacting them, but if you do speak with them on the phone then you better be familiar with their work and as appropriate drop a comment. Profs don't like brown nosers but a little genuine flattery might convince them to try to push the decision making along. At the very least perhaps you can wrangle from them some information: a) how many slots in screen writing are not yet firmly filled? b) What are your chances low, medium, high for those slots? c) Have they established a waiting list yet, and if so how many people are on it?
While acknowledging that they have their process and priorities, you might also indicate that you participate on a forum(s) and know that part of the way prospective students evaluate a program is how they are treated during the application (and acceptance/rejection/wait list) process.
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I do not know what the "rules" are at your 2nd choice school. I know you said you had to decide in 10 days, but don't know whether you also commit a non-refundable tuition deposit immediately. While "not fair" to the other school and to the other screenwriting applicants there, if your financial commitment to accepting at your 2nd choice is not too steep and you still have not heard from Chapman then you might accept there to give the Chapman process more time; and then if accepted at Chapman release your spot. You might also find out whether your 2nd choice school would offer you perhaps an additional 5 days to decide.
It is a challenging set of choice points and I will picture you having clarity as you weigh your options and actions. Hopefully some of this has been of some assistance. What you communicate with them (as well as any subtext) might be important. Sometimes the best action to take is inward (confidence in yourself, patience, calm) and doing the rest of your life; sometimes some other outside action is preferable.