Liquorice

You can always apply for a 60-day extension to 'visit Thai spouse', which will effectively change the date you need to renew your Non Imm O ME visa, if that helps. You can also obtain a re-entry permit for the 60-day extension. Are you aware with the Non Imm O ME, it's possible to stay in Thailand for almost 17 months, with only 3 border runs and 3 x 60 day extensions, before applying for a new Visa.

Using the combo method, I'm not sure Immigration would accept an Embassy Income letter for only 660K Income. The rule was always an Embassy letter confirming an income of no less than 65,000K per month, OR 12 x monthly overseas transfers deposited in a Thai bank and funds deposited in a Thai bank totalling 800K per annum. For the funds part, those using the 800K must provide evidence of the 800K being deposited in a Thai bank account 2 months prior to, and for 3 months after the extension is granted. They can then withdraw from said amount, but must leave a remaining balance of no less than 400K in the account. i.e. 800K for 5 months, 400K for 7 months. From order 654/2564; Criteria for consideration. Clause 4). At least 2 months prior to the filing date and 3 months after being granted permission, an alien must have a deposit in a commercial bank located in Thailand of no less than 800, 000 Baht. After being granted permission for 3 months, an alien can withdraw said deposit and must have the remaining balance in the bank account of no less than 400,000 Baht. When using the combo method, the same rule applies to the funds part, just the same as it does if purely using funds. Clause 5). An alien must have an annual income and a deposit in a commercial bank located in Thailand with total sum of no less than 800,000 baht as of the filing date. The said deposit must maintain in the bank account prior to and after the permission is granted and the withdrawal can be made under the same conditions in the criterion 4). The contentious and often misinterpreted part here, in clause 5, is ''and the withdrawal can be made under the same conditions in the criterion 4''. It basically infers you can withdraw half of the funds, or at least that is how many expats and Immigration officials interpret it, ............... but that isn't what it actually states, the important line in clause 4 being ''and must have the remaining balance in the bank account of no less than 400,000 Baht''. That feature isn't missed by my IO, who insist that when applying using the combo method, the minium funds balance must be 400K and that balance must be maintained throughout the year, to comply with clause 4. I'm not suggesting that is correct, this is how fickle and ambiguously written these orders actually are. If you're getting away with 200, 300, or 350K funds (as I've read), using the combo method, then my advice would be not to create waves.

The criteria for using the combo method is listed in order 654-2564. Read clause 4 and 5. RTP-Order-No.654-2564-1RevisingClause2.22oforder327-2014 (1).pdf

That is incorrect advice. When using the combination method of monthly overseas transfers and funds in a Thai bank, totalling 800K THB, the funds are subject to the same rules as for using the 800K in a Thai bank method. i.e. The funds must be maintained for 2 months prior to and 3 months after the extension is granted, then funds can be withdrawn under the same criteria as when using the 800K method. If you are using 400K funds, then you may be permitted to withdraw half, 3 months after the extension is granted, leaving 200K for the remainder of the year, or at certain IO's they insist you must maintain a minimum of 400K throughout the year. The interpretation varies at IO's due to the ambiguously worded order.

I read it clearly and understood his meaning the first time. You mean, as in, when you MOVE to a NEW address

Do enlighten us with the correct information then! If, as @edwardflory stated, you move to a new permanent address, when should you file a new TM30?

Manually yes.

Not 7 days after the due date. You get the error message to report to your IO.

In that case, a confirmation letter from your Embassy or obtaining a Yellow house book, would be an alternative, although more costly and more inconvenient. I've noticed Thai banks have moved away from listing documents required to open an account for foreigners on their websites. Bangkok Bank in particular, where I was informed rather than a single policy, now each branch can construct their own requirements to open an account for foreigners. Times have certainly changed.

You can open a bank account on any type of entry. Most banks require a residence certificate as proof of address and a recommendation. The account should be opened locally.

You can do it only in person up to 6 days after the due date.

I suspect the IO's were reluctant (poorly trained/lack of ability/knowledge) to process such applications. Much easier to advise you go out of Country to obtain it, rather than admit they don't know and lose face. I am aware of at least one local expat who managed to obtain a Non O for his son from Immigration, but it wasn't plain sailing.

Open the link; 8. FOR PROVIDING SUPPORT TO OR BEING A DEPENDANT OF A PERSON WHO HAVING RESIDENCY IN THAILAND (NON-O)

@Maestro is correct. According to the OP, his son entered as a Tourist (VE/TV?) To piggyback his Fathers' extension, he must have Non Immigrant status. He can apply for the change of status (Non O) at his local Immigration office. Procedure here; VE-TV to Non O Dependant.pdf No. 8 on this list; https://bangkok.immigration.go.th/en/issuing-and-changing-type-of-visa/

Online, 14 days before the due date, up to and including the due date.

If you ask a bank, they'll tell you most Thais are aware of their spouse ATM card PIN's and withdraw the maximum daily amount until empty, before they notify the bank of their demise. Provided you are the sole beneficiary of the estate under law, then there is no comeback. This is where making a Will is a necessity IMO.

The POA ends for me, but the wife still has the power to sign for funds or transfer. I also stated there is a Will in place.

Really, can you provide a link to that information, or is it just your opinion.

It does? Have you read the conditions of the POA we jointly signed, and how!

As I've been stating. There is a legal procedure to follow to have foreign documents authenticated to be acceptable as genuine by Thai authorities.

We're not in the UK. Different Country, different laws. https://www.samuiforsale.com/knowledge/inheritance-laws-thailand.html

For Immigration purposes, the account must be in the foreigner's sole name. You can add a person to your account though by signing a Power of Attorney form that the bank provides, which gives them access to your account, but on statements, letters etc, only your name appears. Hell, Bangkok bank even gave my spouse a separate debit card for my account when I gave her POA. To navigate through the Thai Inheritance laws of succession after death, a simple Will suffices as to who inherits the deceased estate and avoids the probate process. (Unless someone contests the Will).

Thailand doesn't have Notaries as such, they have lawyers approved to act as a Notary. I suspect what they told her is the document and translation must be 'legalised' by the MFA to be acceptable. No different from affidavits to marry or foreign diplomas to be accepted in Thailand.

No, they have an unauthenticated UK death certificate and a translation certified by a Thai lawyer. They're checking out the Death certificate is genuine along with if anyone else is entitled to the estate, as @OneMoreFarang pointed out.

They'll take no notice of a lawyer's letter. She'd need to sign a POA for the OP to conduct affairs on her behalf. My wife has POA to access my account and a Thai Will along with a Thai death certificate, Bangkok Bank assure me funds would immediately be released to my spouse in the event of my death on production of those documents. At minimum, the lady in question will require a Court Order to release said funds to her, after proof she alone is entitled to said funds.