Second option after completing the first 1 yr extension, ask if your local office will allow one spouse to "change the reason for extension" and go "dependant" on the other.
You cannot get a non-o "retirement" dependant in country and most?( if not all embassies ) have stopped issuing them.
Some embassies will do a dependant visa IF the primary obtains an OA visa.
Neither can be done in Thailand.
The dependant visa for "retirement " is fundamentally dead.
IF you are able to have another visa and extension, then the second year you may be able to "change the reason for extension" to dependant but not all offices will allow it and in the time it would take to get to that point it may not be available at all.
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