We're still in the process of getting all the documentation together (no hurries) but I did have a few excellent finds that are worth sharing as they would be very helpful (and cost saving) to future readers.
Getting a certified translation to English for the girl's Thai birth certificate was done at the Thai Department of Consular Affairs on Ram Inthra Rd. in Lak Si, Bangkok. For recent births (can't remember the cut-off year) these are easily obtained. Price - free. You must, though, make an appointment first.
Since the mum was born before the cut-off year we had to look elsewhere for a translation. I ran across an excellent and helpfui educational and resource site called ExpatDen which covered all types of translation needs in minutiae. We originally had our target set on First Choice Translation Co., Ltd. located in Samsen Nai, Bangkok but I found their price of ฿11,500 to be outrageously steep. Lead time is 6 days and travel to their office is required. So I went to a recommended certified translator site provided by ExpatDen. Bangkok Translation and Interpretation Service
Quotes can easily and conveniently be done on-line without the need to travel to their office. The Thai document can be sent electronically either via their website or by email. Replies for quotes are rather immediate. Translated documents can be return sent either by email or both email and post, if the original is required. Lead time is 2 working days, whilst the delivery time for the original translated document is excluded.
Translations are certified, review and proofreading is done by 2 linguists, and they offer unlimited revisions in case of errors.
The price was an absolute shocker. ฿550 for the translation and ฿50 for the postal fee. We are going to our favourite Italian restaurant this late afternoon to pig out for free thanks to the savings.