2 hours ago, CecilM said:

Easiest solution if all parties can agree. That would require them making it work and actually living together (photos for visa application & possible visit by Immigration Officer). 

If willing to stay officially married, but not wanting to live together, only a bit less convenient is multiple entry Non O visas from Savannakhet. There is no requirement, when using these, for you to cohabit with your wife.

18 hours ago, Pib said:

From Bangkok Immigration

https://bangkok.immigration.go.th/en/visa-extension/#1610937437663-90b1feab-b48a

 

See line item 18: In case of being a family member of a Thai National.  There is no mention of Thai children age requirement.

 

VISA SPOUSE / THAI CHILDERN

Criteria for Consideration

1)  Applicant must have been granted a non-immigrant visa (NON-O)

2)  Having proof of relationship

3)  Having evidences of nationality of Thai spouse or Thai children

4)  In the case of spouse, relationship must be de jure and de facto

Documents to be submitted

1)  Application Form for extension of temporary stay (TM.7) attached with one photo of applicant

2)  Copy of passport first page with photo and copy last stamp, first visa, last visa, departure card(TM 6), evidence of report address, evidence of report 90 days

3)  Evidence of relationship

3.1  In the case of spouse
– Marriage Certificate (khor lor 2 and khor lor 3) or ;
– Marriage Certificate from abroad must be certified by the Embassy and the Department of Consular Affairs in Thailand

3.2  In the case of Thai children
– Copy of Birth certificate and household registration of child/children

4)  Copy of Identification and household registration of Thai spouse or any other document proving Thai nationality issued by authority or governmental agency concerned

5)  Copy of House lease agreement, Identification and household registration of owner with certified signature

6)  Application fee is 1,900 Baht

7)  Any other relevant documents which may be required for consideration

REMARKS:

1)  Applicant and spouse must contact in person for an interview

2)  The originals of required documents must be shown to the competent officer and photocopied with certified signature by applicant

part my confusion that they seem to mix in spouse almost everywhere.

what if i am divorced ( in the process) and i dont live with the spouse the same household?

assume it would be just fine to register my son to my new address as an adult, and say we stay in the same household, even though the meantime he stays at the university and not at home, neither with me or his mom.