H1/H4 Dropbox Visa - Parents/Kids - One Receipt Number

[PJRR]

I have an H1B visa, my spouse has an H4 visa, and both of my children (12 and 9) have H4 visas. We're all eligible for drobox appointments, and I've paid the fees for all four of us using the same receipt number. I'd want to schedule a drop-box appointment depending on availability, and may I plan appointments for my children (Father/Mother/Child1/Child2) alongside their parents?

I'm also curious if children under the age of 14 require a copy of their parents' legal visa, as I won't have one if we can arrange an interview together (Father H1B/Mother H4/Kid1 H4/Kids H4/Kids H4).

Could you please tell me if you've ever been in a similar scenario or if you have any recommendations?

Thank you.