What are the requirements for switching from Non-B to Non-0 "Marriage"? Of course, under the virus circumstances, without leaving the country,

I don't trust agencies and I would like to do it legally, How does the process look like?

It is not possible to change from a non-b visa entry to a non-o entry while in the country.

It is possible to apply for a extension of stay based upon marriage to a Thai a with non-b visa entry. It only requires the normal document and financial proof as any application for the extension.

See: Marriage Extension Requirements 2.pdf

I see. Thank you for your explanation. Please, kindly tell me, once you've got an extension that way, can the employer cancel your visa once you quit the job or you can stay in the country and find another one?

1 hour ago, Druidian said:

I see. Thank you for your explanation. Please, kindly tell me, once you've got an extension that way, can the employer cancel your visa once you quit the job or you can stay in the country and find another one?

Nobody can cancel a valid visa.

Only a extension of stay can be canceled and after applying for a extension based upon marriage your extension would not depend upon you working and could not be canceled if you lost your job.

Once again, thank you for your help. I think this is the last question concerning the matter; say the extension of my non B expired in six months but I would like to switch to that non 0 "Marriage" extension right now, is it possible to do it or I would have to wait around six months and apply for it just before my non B extension expiration date?

12 minutes ago, Druidian said:

Once again, thank you for your help. I think this is the last question concerning the matter; say the extension of my non B expired in six months but I would like to switch to that non 0 "Marriage" extension right now, is it possible to do it or I would have to wait around six months and apply for it just before my non B extension expiration date?

You could apply for it now if your employer gave you a letter requesting your current extension be canceled on the same day you apply for the extension based upon marriage,

Thanks so much for your answers. Please, one more question; after getting that non 0 "Marriage" extension, could I get another one once that non 0 was right about to expire?

37 minutes ago, Druidian said:

Please, one more question; after getting that non 0 "Marriage" extension, could I get another one once that non 0 was right about to expire?

You can apply for a new extension year after year without ever leaving the country if you want to.

And if I got that extension with an agency help, could I get a new extension in one year myself?

29 minutes ago, Druidian said:

And if I got that extension with an agency help, could I get a new extension in one year myself?

Yes you could do it yourself next year.

Thank you for all your help. Is there any agency near Chiang Rai you could recommend to me, please? If you cannot post it in here, please, pm me.