When having obtained a 12 month extension based on marriage to a Thai, With multiple entry, can I leave Thailand for 7 months (family reason) then return to Thailand say one month before the next 12 month renewal process starts again?
As a second question, is it possible to convert to a DTV whilst in Thailand from a marriage visa?
TLDR : Answer Summary
If you have a 12-month extension based on marriage to a Thai national, you can leave Thailand for up to 7 months as long as you have a re-entry permit and return in time for your next extension application. However, you cannot convert from a marriage visa to a Tourist Visa (DTV) while still in Thailand, as tourist visas must be obtained from Thai embassies outside of the country.
DTV VISA RESOURCES / SERVICES