The best way is apply thailand tourist visa in laos vientiane. You can enter from border with visa only. Arrival visa is not allow from borders. Its only cost $40 and about 3 days
I think u may have an interview email soon. Ur interview date may monday. If u can show ur bank account from ur mobile phone at interview and u have good money evidence u may get visa on monday
sponsorship letter is about u have to pay all the cost of ur childrens. And family certificate is the list of ur family members approved by goverment(some other country may different).
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.