I am curious. If a Thai who suffers from bad health, was unable to go the the US embassy in Bangkok to have some documents notarized could she have someone go for her. The documents concern an inheritance she is entitled to. The  the American investment company suggested she go to the embassy and have documents signed and stamped (application forms for  and transfer of funds, death certificate etc )at the US Embassy. I am wondering if she could get some kind of notary public to approve a friend o r relative to go in her place. From what I guessed from scanning the US Embassy's website, the documents must be signed in the presence of embassy staff. 

Not endorsing this website since I have never used them. I did a quick web search and found this link.  Hope it can be of some help to your situation.  

 

https://www.notarize.com/knowledge-center/find-a-us-notary-public-abroad