Just a check.
Brother arrived with a marriage O, single, 90 days. E visa.
He cannot get a 30 day extension on that ?? He would get 7 days to leave the country ??
He had a 60 day family extension back in Jan 2023 bit not on this visa entry. My belief is family extensions are once a year not once per visa ??
This is Chiang Mai in case there is any regional issues.