I wish I had a great suggestion but I don't. It's simply a matter of figuring out what the problem is and eliminating it. All you can do is try one thing and then another until you can determine why they started this.
It may be just because you took the box from the soon to be baby's room. Hopefully they will adjust on their own and stop or you can eventually figure out what will make them happy.

Good luck because I know it's very frustrating. Hang in there and don't give up. You will come up with a good solution for you all. It's just going to take a little time.