I am a Russian citizen married to a US citizen. Last year I adopted a Russian child, with the permission of my husband. Now he wants to adopt my son from me, but we all live in a third country and it seems to be impossible to do it here. What should we do now? Do we need to go through an American adoption agency or we can just hire a lawyer in the USA to represent us? Does he need to go to Russia to adopt my child there first? Do we need a home study?

You should probably contact a lawyer about this. If you are all US citizens, then by all means contact a lawyer in the US.