It depends on what exactly you were on.

Have you been in Thailand for less than 90 days from the initial visa? Then you are fine, you don't need to do anything with your visa stamp.

OR

Have you already applied for an extension at the local immigration office in Thailand? Then you must cancel the latest extension once you are back to Thailand, IF you want to apply for any other extension in the future.

If you will not apply for an extension hereafter, and will travel to Thailand only on a tourist status without extension, you can leave it.

If you were on the Non-ED from the embassy in another country for 6 weeks, that means you were still on the first 90 days from an initial visa. If this is true, you are fine, as the initial entry stamp cannot be cancelled.

You need to cancel your stamp only when you have already applied for an extension at the local immigration office inside Thailand.

Another thing is, do you want your daughter to have a chance to live in Thailand long-term in the future?

If yes, you have to cancel her extension officially before she leaves Thailand. To do it, the stamps have to be transferred to a new passport.

(I cannot come up with a reason for her extension that is not required to be cancelled, such as "being over 50" <- no reason to cancel)

If an old and "supposed-to-be-expired" extension is remaining, it will cause an issue when the holder wants to apply for a different extension in the future, even after years have passed.

Same for you, if you are on an extension currently, and there is even a slim chance you will be back to Thailand as not-a-tourist, you should cancel your extension officially before you leave.

If none of you will ever be back to Thailand other than a tourist for short holidays, you can just leave.

@Michael **********

, yes, your landlord is supposed to provide one.

You also need a TM.30 receipt with your current address in Bangkok.

Don't worry about TM.6 if you don't have. It's been suspended for years for travellers coming by air.

You have to go to the Chaengwattana office, Government complex building B.

The One Bangkok office wouldn't deal with 90-day reports unless your extension has been issued by BOI/IEAT.

If your son didn't get an overstay stamp before when he was overstaying, he got just lucky.

@Peter ***************

, to have to do if you are on Non-OA visa.

@Peter ******

, there is no "first month" limit.

@Gui***

, if you will do volunteering for an organization, it will be a Non-O for that like kind of employment as volunteer, with work-permit.

If you will work for a standard company, no Non-O for employment.

@Andy *****

, departure information fields are not mandatory (they are without red stars). You can leave them blank