Dear sir.
I am a citizen of usa, I married a man with 4 children his immigrations papers are pending, but as a step mother I file for them, now the embassy ask for DNA test and to fill up an affidavit of residence and paternity maternity form, who has to fill it up me "the american step-mother and petitioner" or their biological father whoes paper are pending?
Thank you.

It's the father's responsibility, not yours.