Child visa stamping before parents' stamping

Current status -
Child is in USA on H4.
Can child (above 18) go alone for visa stamping to home country, while parents are on valid 797 and not having approved stamped visa?
If not, H1 stamping of a parent required before child’s visa stamping? Or both parents’ visa needs to be stamped before child’s visa stamping?

Child above 14 may go to the H4 interview or interview waiver aka dropbox and submit copy of parents passport with visa pages ( even if expired), copy of valid I-797 and copy of their I-94 last entry record. Note that the H4 will also need to carry other documents for primary H1B such as the copy of employment verification, last three paystubs.
H4 child above 14 is not required to submit valid US visa copy for their parents. This only applies to child below 14.