Go to the embassy website.
http://bangkok.usembassy.gov/immigrant_vis...estions.html#12it states:
"Q: How can the children of a visa recipient follow to join the parent in the USA?
Children of K1 and K3 visas holders only are eligible for derivative visas (K2 and K4). Provide us with an address in Thailand to send "packet 3" documents for completion by the childrens' current guardian. After the guardian returns the complete checklist of required documents, we send out additional instructions. Then we schedule an interview for the children. Please note that the childrens visa must be issued within one year of the parents visa.
For other categories of immigrant visas, the petitioner must file a separate petition for each child"
Send an e-mail to:
" Please send an additional email to visasbkk@state.gov with the following information
Subject Line
1. Must contain the words “Inquiry”
2. Case Number: Include the case number (with prefix of BNK)
3. Applicants surname: include in the subject line.
Text of Message: Include the full name of the petitioner, applicant, type of visa, nationality of applicant (Thai or other) and your contact information in the first paragraph. Follow this with your specific concerns in the subsequent paragraphs."
Or you could use the forms online on the website. Rin and I did the same thing. She came in April 2007 and her children came in October. I sent the embassy the necessary docs (DS230-part 1, passport photos, etc) in mid-September (when we returned to Thailand) and requested interviews for the children the first week of October (let them know we had departure on October 12th). They were very accomodating.
Goodluck!
John