I had to prove that my niece and nephew are blood related to me by sending my birth certificate and my sisters birth certificate to show we have same parents and I had to send my niece and nephew birth certificate and letters from their doctor and school to prove they lived with me all year. I filed on January 22, it was accepted January 29. I received a letter requesting proof on Feb 12, I faxed 47 pages of verification on Feb 16 and mailed it to theme Feb 16 on March 12 they sent a letter stating they got the stuff I sent and they have until June 6 to finish the review.
