I’m guessing you have an O visa. When you get a 1 year extension you can choose to extend as married or retired. The financial requirements for married are cheaper but the amount of documentation is more and the process may take a few weeks and may include a home visit. Extending as retired is more expensive but there is less documentation and you can get it done in an hour or two.
Every Thai has a residence and it is documented in her blue book. She will know what it is.
I, an American, was able to get a yellow book. It’s the same thing only yellow. I was able to use is as a residency document when buying a motorbike recently.
Probably what you need is her blue book. It sounds like you are describing the chanote which is the land document. Bring what you think they might want. Both of you visit the immigration office. You either have what they want . . . or not. They will tell you what they want and then go get it.
Maybe someone from Korat will comment but in the end the immigration office is the definitive source for the answer to your question. You might as well find where the office is located and introduce yourself. While you are there ask what you need for your 1 year extension and how to do 90 day reports.