Usually the marriage certificate if in another language has to be translated to English and has to be notorized or have a certificate of translation attached. That is what I was told, but cannot be sure.
You can get information from the Ukrainan Embassy here in NY..they can help with information regarding these services whether here or in the Ukraine.
Here is a link to their Embassy, they may be able to help you get those legal documents here, if USCIS require them.
http://www.ukrconsul.org/ABOUT_US.htmI married in England, so translation was not needed, but my marriage certificate was accepted by USCIS and I gave them nothing else, except a copy of my original marriage license for back up.
Regarding the child, as the same as the adult, you will need birth certificates. Again translation is needed.
If the child has a father and the father has rights, he may have to give permission for the child to leave the country, let alone move to the another country.
Best to sort that part out before applying, could delay things if not. Each country have their own laws regarding children and father's/custody rights.
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God Bless America - God Bless Immigrants - God Bless Poor Misguided Souls Too

Mr S.U.