Is it possible for my adult daughter born in the UK to obtain a Thai passport?

Since your daughter was born outside of Thailand, a Thai birth certificate can only be done by the Thai Embassy/Consulate in the country where she was born (the UK). I know in the USA, you need to get a birth certificate from the originating authority (the state), and then authenticate the birth certificate at the state and federal level before it's presented to the Thai Embassy. They will also need two passport photos of your daughter. Some other documents you'll need are your marriage certificate, your wife’s Thai ID card, Thai passport, and Thai house registration info, both your wife and your UK passports, and another form of identification card such as a driver’s license. There were a few forms to fill out (in Thai). We did not have to physically visit the Embassy, we were able to mail notarized copies of everything (except the original authenticated birth certificate). The process was pretty easy if you have above documents. I’d imagine the process would be similar in the UK. The Thai Embassy in UK should have some instruction in English, or give them a call. The Thai Embassy in USA has always been very helpful!

One small note: The Thai birth certificate contains height and weight at birth, but our state does not have those on the birth certificate! The Embassy had us provide a document from the hospital with this information to put in the Thai birth certificate.

Thailand passes citizenship through blood line hence your daughter can have the Thai citizenship and passport

She should have Thai passport

My daughter was born in the uk teesside now living in Thailand duel passports

Dont mess around on here go to the Thai Citizenship group and you will find clear instructions how to do it

of course she can if she has a thai mother<

Is she on someone's Taam Bien Baan? Does she have a Thai id card<

both needed before passport is issued