Claiming Newborn on Taxes!

Its that time of year again. My accountant informed me that I can claim my foster child on my taxes for 2012 as he was a newborn placed directly from hospital into my care. My complication, I do not have his ss#. I have placed multiple calls to my CW and she states she is waiting to hear back. Is there anything else that can be done? There is possible issue in which mom may rush to file and then if I file afterwards and IRS complications arise. Any ideas how I can get his ss#? Is a trip to the SS office needed? He was in NICU she had no contact allowed, so I am not even sure if she received information to apply for his SS#. But she is quite difficult and uncooperative so... Any advice welcome!