I flew out of Bangkok last Sunday with two passport. At the passport control the border guard took me to a separate stand where they copied my entry stamp with the DTV from my old passport to the new one, and also put the exit stamp in the new passport. He specifically told me I need to carry both passport when I come back to Thailand. The whole process took like 5 minutes, he didn't ask me any questions and was very nice and polite

@Iuliia *********

I'm pretty sure I did just write FMS followed by the numbers and got granted the visa. (It was like a month ago, so I'm second guessing myself now haha). You can also email/text the embassy you're applying to directly and double check with them.

@Iuliia *********

does your passport say ФМС and some numbers after? Just type FMS and then the numbers