In addition to asking for the usual 30 day extension on my "Exemption on arrival" I need to transfer my arrival stamp from my old passport to my new passport, obtained since I arrived. I have the embassy letter requesting it Does anyone know if I can do that at Muong Thong Thani also? Thanks.
TLDR : Answer Summary
The process of transferring a 30-day Visa Exempt entry stamp to a new passport is not standard. Typically, you will need to show both your old and new passports when exiting the country, rather than transferring the stamp.