The first thing you'll need to do is to prove your child's citizenship.
Do you happen to have lost the child's certificate and are unable to get another one within 10 days?
I haven't lost the child's birth certificate.
But my child lived outside the United States for quite some time.
In that case, you'll need to provide a document that proves that your child lived in another country and does not have a social security number. You could use records like the child's school records or employment records.
Is it possible to get him a number assigned before the adoption process is completed?
It is possible, yes. In some cases, we do assign a number before the adoption process is completed but you may want to wait.
What other documents can I use as proof that my kid decided outside the US for a long time?
apart from the ones mentioned before, any document that shows long-term residence in another country would be enough.
And what documents can I use to prove my identity?