see the following i got from that act. seems my lawyer

is correct that I-824 is for kid who is not in the usa:

In cases in which the principal adjusted status in the U.S. and the derivative is applying for a visa abroad, the derivative will be considered to have sought LPR status on the date that the principal filed Form I-824 to initiate the child’s follow-to-join application. Because Form I-824 is not the only way to initiate this process, DOS instructs posts to seek an advisory opinion in cases in which some other “concrete” step was taken. What constitutes a “concrete” step has not been delineated.