H4 Visa Stamping

My wife has visa interivew scheduled in November. She has previous h4 which is expired couple years back.

My kid is born in India and 1 yr old.

Based on the drop box criteria, my wife is eligible for drop box. But my kid has no visa stamping yet.

do they have to attend the visa interview or both of them are eligible for drop box.?

if both are eligible for drop box, would it be a issue to attend the visa interview still?

Child below 14 is eligible for dropbox.