The 4547 can be completed and e-filed with the 1040. Or it can be mailed in separately. Or it can be filed online when the website is [eventually] up. Or - supposedly the government will get the new birth records from Social Security and handle it themselves. This last one I would not rely on AT ALL.

The form just doesn't ask for the new baby info. It asks for the filer's info and relationship. The standard is easy - mom or dad from a joint return.  It gets more difficult when mom and dad do not file together, or are even married.

I'm taking the position of I will complete the form and separately have the taxpayer sign it and mail it in. Makes me look good that I'm helping them get another benefit, rather than just another piece of paper within a 60 page tax return.