Got 60-day extension based on Thai family today at Chiang Rai immigration. Here are the documents needed if anyone needs to follow suit and not sure what to bring. And don’t forget your wife needs to be present as well.
Tm7 application form + 1 photo
Passport and copy
Visa page copy
Tm6 entry card in passport copy
wife ID card copy
Wife housebook copy
Marriage certificate copy
Rental contract copy (if you don’t live at the address on your wife’s housebook)
Kor ror 2 form - can be obtained at the Amphoe office next to immigration for 20 baht
1900 baht