The name of the statute is the Child Status Protection Act of 2002. The section relevant to your situation is Section 3. There is no need to file an I-824 for a child in your situation, where the child is already in the United States. But it probably wouldn't hurt anything if filing it; it would just be a waste of money.
it is right that There is no need to file an I-824 for a child where the child is already in the United States?