good to know, then as people pointed out he either tries it and see if it "slides thru" OR he goes for the one 60 day visit thai family extension he can get to buy another two months for the seasoning
Okay as far as 400K baht for the banked money method based on marriage to a thai, the funds only need to be in the account for 2 months before you apply for the extension.
AND
As far as the 400K baht that has to be in the account ALL THE TIME for the banked money method based on retirement,
There is no leeway on either, and I've had people denied extensions because the balance fell below the threshold for a matter of hours (even though the daily balance still hit the requirement)
That was a fail on your part and you could very well find you painted yourself into a corner by not following the seasoning requirements.
DEFINITELY go apply for the extension as soon as your office allows (45 days before with some 30 days before with others) so that IF they deny the extension (which they are well within their rights to do) you have plenty of time to plan a trip out of the country to get a new Non-O visa and start the whole process over againg.
There are no fines for overstay on a child under 15 and there is no banning for overstay on a child under 18. If they're small kids, just let them overstay, nothing will happen, not to the child and not to you.
I know foreigners here with children on multi-YEAR overstays
no they don't take submissions in person. YOU need to find a way to get the file size small enough AND include all the required documents
you can't EDIT the application but you should have an "add additional documents" option once they sent you the request and that's the status IN the eVisa online system