What documents are needed to convert a NON-O single entry visa to a one-year extension based on marriage?

You could take a look at my recent post on this topic ... I am an American expat and applied for my extension in Chiang Mai ... From the comments received, the documents requested at the various immigration office's vary and each submittal may be unique even at the same office. You should be able to get a list of the required documents and blank forms at the immigration office where you plan to submit your application. The immigration officer may request additional documents during your application review ...

If it is based on being married to a Thai National, the best option is to visit your local Immigration Office and ask for the hand out with requirements. As there are over 70 different offices nation wide and some of them ask f.e. one picture more or less etc there is no one list fits all offices.