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
You can leave Thailand for 7 months on a marriage visa extension with a re-entry permit, as long as you return in time for the next extension application. However, you cannot convert a marriage visa to a DTV while in Thailand, as tourist visas must be obtained from Thai embassies outside the country.
DTV VISA RESOURCES / SERVICES