I visited Chiang Mai immigration today to ask some questions about a 1 year extension of stay based on marriage, but the volunteer I spoke to didn't seem too sure, so thought I'd check here.

I'm currently on a 1 year multiple entry non-O based on marriage which I got from Savanakhet & this will be my first 1 year extension.

I put the 400k in my Thai bank on July 1st. I believe this means I can apply on September 1st. Although the volunteer mentioned because it's my first extension of stay, the money may need to be in my bank for 3 months rather than 2. Can anyone confirm this?

My current visa expires on September 3rd but my last entry stamp is valid until September 26th.

I have the option to do a border bounce before September 3rd to get another 90 days, but I'd rather not do that unless it's absolutely necessary.

The wife and I were planning on applying for the visa at CM immigration on September 6th.

As long as we have all the correct paperwork, are we likely to run into any issues with this timeframe? (especially if they say the money needs to be in the bank for 3 months rather than 2).

Should there be any issues when we apply, would I be able to extend my current stay past September 26th at immigration?

Final question: My wife changed her surname to mine a few months after we registered the marriage last year. She has a certificate for this which I will include in the application. Do we need to update our original marriage certificate (which has her old name) or is it fine as it is?

I just want to make sure I've got everything in order before applying. Thanks!