they both arrived on nonO dependent visas. We processed our extension of stay at SP immigration, so now they are both on extension of stay based on their dependent status.
That used to be the case. Due to Covid, MoE (or some other official body) wrote a formal request for Immigration to allow for such changes to be made in country. Some immigration offices allow, others do not.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.