It seems all you're trying to do is cut one visit to the immigration office out of the process so you can show up with BOTH passports when the extension is due and get the stamps moved along with filing for the new extension.
You can indeed do both at once IF you get the new passport close to the date you're next extension is due.
I think this thread went as afar as it can. We're just rehashing the same stuff over and over.
I messaged you about this post before I even let it on asking what you were trying to do.
You are far from the first person to have this happen.
What it sounds like, is that you failed to cancel your ED visa extension before you left the country.
You need to realize that just stamping out does not cancel an extension officially.
What's going to happen is, when you go to cancel the ED extension they will fine you 500 baht per day for every day that you didn't cancel it up to a maximum of 20K baht
It's not technically overstay, insofar as you cannot be banned for it, and your current entry stamp is still valid. It is a fine for failing to follow procedure in canceling an extension.
If you were on an extension based on higher education you could have got an additional year extension after you graduated under the ED Plus program and I don't know why your University didn't tell you that.
Anyway, you won't be banned from the country but you will be fined 500 baht per day.
Take the documentation from your University saying you stopped studying on XXX date to the immigration office that issued you your extension and cancel it officially.
You renew the passport (before you apply for the next yearly extension) and as soon as you get the new passport you go transfer the stamps and then you go get the extension.
This is the transfer stamp form they use in Bangkok (if that's where you get your extensions) It lists the copies etc you need to transfer stamps when you get a new passport
I am doubtful your child has any visa 😮 and it's far more likely they have a yearly extension of stay FROM an original O visa. (the stamp should say "extension of stay permitted until")
If they have the stamp I mentioned (the extension of stay stamp) once you get the new passport you take both passports to the immigration office that issued the extension and get the stamps transferred to the new one.
Then you just use the new passport when you do the application for the next yearly extension
and as much as you don't want to deal with them it's going to take you slogging over to that office and seeing if they accept the 12 months of transfers of 40k a month for a marriage extension or not 😕
AND
if they don't you have no alternative but to bank the 400k for 2 months before you apply for the next extension 😮
You're wanting an answer from the group when it's only the immigration office you deal with that can give you the real answer
post on a Korat group and ask, someone else has tried to do it before you I'm sure 😛
As you correctly stated you're not on a Non-B visa now you're on an extension from it, and you wouldn't be applying for a Non-O visa based on marriage you'd just be changing the reason for your extension from one based on employment to one based on marriage to a thai
You can do it by cancelling the extension you're on based on employment with documentation from your employer saying you stop work on xxx date,
AND
You get all the documentation you need for the marriage extension (400K baht banked in a thai account for 2 months before you apply, all the copies, marriage documents, house book thai i/d etc bank letter, bank statement, photos, etc)
You go to the immigration office (with your thai wife as she's the reason you can get that extension) you cancel the extension based on employment, and you immediately apply for a new yearly extension based on marriage to a thai.
You'll pay 1900baht, they'll give you a 30 day under consideration stamp and then when that runs down you go back to get the year extension inked into your passport.
All you're doing is changing the reason for your extension not changing visa types.
OR
You could cancel your extension, then bounce out/back to get a 60 day free entry stamp and apply for the in country 90 day Non-O visa first for 2000baht at the immigration office then when that runs down you apply for the yearly extension.
1 - yes it is possible to switch reasons for your extension
2 - no, you wouldn't come back on a tourist visa, you'd come back free stamp entry on a 60 day visa exempt and then apply in country for the 90 day Non-O, then the year after that
3 - you need a TM30, lease, land lord i/d house book, etc
GO to the chiang mai immigration office and get the hand out listing the requirements for a year extension based on marriage to a thai.
This is a general list of what can be required it is NOT office specific so that's why I said go to the C/M office and get their hand out