Received a receipt of I539 (wife H4 dependent), but kids I539-A two receipts not received yet through Mail service?

We have received a receipt of I539 (wife H4 dependent), but kids I539-A two receipts not received yet through Mail service ( courier).
Below is the H4 dependent receipt details which was received on Dec 22, 2024 to my current address through Mail service.
Form I-797C, Case Type - I539,Receipt Number: WACXXXXXX,Name: XXXXX

how can i proceed with next steps as already reached customer care of uscis and they told that there is no data of both kids in system, might be they missed forms or different reason and also they suggested to send an mail to lockboxsupport@uscis.dhs.gov, but we have to wait for 30 days to get response form lockbox,

My H1b extension is approved recently and have my spouse receipt, but kids receipts not yet due to different reason ( may be they missed).

visa is getting expired in Feb 10, 2025.
Is there any legal issue for kids as both kids applications(i539-A) not processed and visa getting expired on Feb 10, 2025?

Kindly share your valuable inputs, Thank you.