Visitor visa drop box question

[kaartman]

Guys, my parents are eligible for renewing their US visitor visa via drop box.
Do they have to submit the documents by themselves or can someone else submit their documents?

Thanks.

[Libra_14]

Guys, my parents are eligible for renewing their US visitor visa via drop box.
Do they have to submit the documents by themselves or can someone else submit their documents?

Thanks.

An agent can also do that at local VFS.