how to file someone who suddenly got a good social security #?

[DDaccountant]

I heard that they can do taxes, where I worked at, my boss said he did it all the time, when someone who is not here legally and uses a fake social security; if they suddenly get a good one, they can retroactively get the earned income credit etc, but how do you go about doing this? I know if you have an ITIN nummber and a ffake social in the w2, well you report the ITIN on the 1040, and mail in the fake W2 with the 1040 ( assuming you are paper filing for a current or prior year) , would you do the same say if they haven't filed taxes in a prior year?, would you send the w2 with the fake ss and the good ss number in the 1040?