What is the best visa strategy for a family moving to Bangkok with a husband on a DTV and a wife needing an internship?

Seems to me the simplest thing to do would be to sort out the visas for your husband and kids in advance of travelling. Get your husband to apply for his DTV and once he has that your kids apply for their own DTV based on your husbands. No harm in doing it early as its a 5 year visa. Once your kids hit 15 they can be fined for overstay so best to get them visas

I am curious, as I saw your previous post, on what grounds will your husband get the DTV? You previously stated he will be retired. It sounds like you will apply for your children to have DTV based on your husband having one. As an FYI, you could apply (e-visa system) for your children after your husband is approved. So it can take some time outside of Thailand to process his and then the children’s DTVs (2-4 weeks). You being on an ED visa probably means you would not be able to travel with them to an embassy in a nearby county. I would suggest applying now, before you head to Thailand. There should be no issue with your husband not being there for 2 weeks later on.

If the kids are under 14 it's irrelevant. Children under 14 cannot be banned for overstay and cannot be fined for overstay. Many people just get them into the country and leave them on overstay. They will just get a stamp in their passport after they leave.

If that makes it easier to get everything sorted until he gets back, then it's a good option.

Otherwise this is the process you would need to follow:

Your husband leaves Thailand and applies for a DTV visa. Waits the requisite time inside the other country for the DTV to be issued.

Once the DTV is issued, you can then apply for the dependent DTV visas (one of the requirements for this application is to upload the already issued DTV of the sponsor).

So you can have your husband get it, then return to Thailand and pickup the kids and go to another country and apply for them. Or he can take the kids and do it all in one trip. Many countries in the SE Asia region are claiming 10-15 business days to process e-visa, so that could mean a significant amount of time outside of Thailand for 2 separate visa approval processes.