I have been told by the US Embassy that Thailand will soon ratify joining the nations that do not require apostilling of documents. I believe this means that they will then accept certified original documents from local agencies in the United States. I have also been told that the US Embassy/Consulate will no longer certify that a person is eligible to get married in Thailand. Their thought process is they have no way to verify what the person is saying so they have stopped doing those a while ago I believe.