Ginger, I would call back and ask again. If you can't get anywhere, then I would ask to speak to a supervisor. I can't believe that they would expect you to split up your family because they can't guarantee connecting rooms. The CM I spoke to said that they have to guarantee connecting rooms for families with children. Granted this was a couple of years ago and maybe they have changed their policy, but if they have, that is not very good customer service to expect families to split up during their vacation. Or maybe you spoke to a CM that was new and didn't know the policy.
That being said, I think you have a good chance of getting connecting rooms with the early check-in. If you can't get anywhere with CRO, I would stress to the CM when you get there that you have to have connecting rooms. You might not get your other requests (if you have others). I know when we requested connecting rooms (when they weren't guaranteed because it didn't involve children), they granted our request but we were unable to get our other requests, like being close to the main building, which didn't bother me as long as I got the connecting rooms.
Good luck and hope everything works out for you.