because under american law, she's the only one that counts, if she does
i'd talk to a lawyer, chances are she can apply for residency
for her and her children, but only if she is not divorced.
or she might have some say on what happens to her son, regardless

your brothers sounds like an asshole
and he's in violation of american law.
how is he going to send her to her parents with 3 children?
probably knowing that its all downhill for her after that?

tough situation