Document required to register a marriage at the amphur

[Karl]

I have a little situation and was wondering if anyone could give me some advise with this;

I am a 50 Years old Austrian Citizen with a Permanent Residency Status (Green Card Holder) to the United States. I got married and registered in New York City and divorced by the Supreme Court of the State of New York.

I wish to get married at a local Amphur in Thailand to my Thai fiancée, 48 years old, divorced after we had known each other for some time. My fiancée has studied in the US and received her Master's Degree there. We are planning to continue our residency in the USA after we get married in Thailand.

I am aware that I would require a clearance from the Consulate, an affidavit stating my legal freedom to get married , but I am very confused who would have to issue it. I had visited the Austrian Consulate in New York, and was told to obtain this document from the Austrian Consulate in Bangkok. I then contacted the Consulate in Bangkok and was told to get this certificate from a city office in Austria since they are not authorized to issue it. But I can't travel to Austria just for this document. And how would they know if I live in the US since 1977 and have no record of my previous marriage there. My divorce document should be proof enough.

I'm hoping to find someone who had a similar situation and would be able to point me into the right direction.

Thank you so much for your help in advance.

Karl