H1B and H4 Appointments

[Vijay Vank]

Hello,

I am planning to book a H1B and H4(Son) dropbox appointment for some time in Dec. My question is if I book for both of us and for some reason the H4(son) is unable to travel to India for Dropbox, what happens to that appointment? Also, since both our appointments were booked together and since H4(son) is unable to travel, would my (H1B) appointment be cancelled as well? I know I will lose the money, but would primary appointment be cancelled as well?

Another question is, I know dropbox was extended for 48 months in 2021. Until when is it valid or are they planning to bring it back to 12 month criteria post visa expiry?

Thanks and Regards
VIjay