For K1 Visa, you will no longer need the form G-325A as the form I-129F has been updated and whatever information that is being asked from G-325A is now added on the new form I-129F.
I assume you are the petitioner?
As for her working "illegally", remember that all these papers you will be submitting will go straight to the immigration department of the US Government. If found and proven that she indeed worked for someone illegally, you may have a hard time trying to get her to come to the US. The immigration policy is now stricter more than ever and the US government is very much against illegal activities concerning citizenship and employment.
Best thing to do is for you guys to consult an immigration lawyer.
