thank you very much for your answer!

thank you very much for your answer!

Do I have to mail the I-94 form to CBP before they try to apply B2 visa or just leave I-94 with their upcoming visa interview? if possible, could you tell me a little bit of detail. sorry that I am asking too much :-).

They have perfect records until I find this yesterday. they have been here in U.S.A. three times, that was their third time.