Patrick, you can apply for a 60 day extension "visit thai family" with your current Non-O Visa at your local immigration 30 days before it expires for 1,900bt based on marriage to a thai national, that requires no money to be in your bank so should give you more than enough time to sort out the seasoned funds in your bank account and apply for your extended marriage visa.
David in the same position as you just arrived in ASQ based on having a British/Thai son on Non O visa. You are correct there about the process. Do you know once the single entry is expired can you apply for a new Non O in thailand and stay longer without leaving the country? Thanks.
do you have to be married to apply for the years extension? I am on a Non O based on having a Thai son. I've just arrived in Thailand and now in quarantine but I'm trying to find the best way of staying long term. Any feedback would be much appreciated. Thanks.