If you are chosing to file your I-600 form with your state's USCIS office, please ensure that you submit the correct documents (with English translations) and that you fill out the form I-600 properly.
I have learned that there are several families who have had their I-600 petitions denied because they submitted an incorrect document with their petition or because they filled out the I-600 form incorrectly.
If in doubt, make sure to check with your adoption processor that the form is filled out correctly. My recommendation is that before you file it with your local USCIS office, you scan the filled-out form and email it to your adoption processor for review.
Also, speak with your adoption processor as to which documents (with English translation) have to be submitted with the I-600 form.
Those denials could have been avoidable...