Not true, cinFLA. The Child Citizenship Act of 2000 provides for automatic citizenship of children born to US citizens outside the US and its possessionsif the child and citizen parent meet certain requirements. Don't know if CCA2K applies to her kids, since it's not retroactive.
They may or may not be citizens at this point (would have to know all the details), but they are certainly eligible for US citizenship.
What is not true.
Why don't you just admit you don't know, period.