Do I need to go to my home country to obtain a dependent visa for my child born in Thailand with a DTV visa?

To begin with, there's no overstay before the age of 14, there shouldn't be any problems, and this has been thoroughly reviewed. However, if you're determined to apply and the issuing embassy doesn't require an interview or in-person submission of your application, you can technically apply online from wherever you like, since the information you provide is self-declared.

I actually know several people who applied through certain embassies while they weren't actually in the country in question, but, for example, in a neighboring country.

You could, for instance, stay in Malaysia for a certain period; however, applying directly from Thailand seems more complicated. I don't know exactly what the consequences would be if the authorities discovered that the application was submitted while you were still in Thailand.

My foreign child travelled in and out multiple times without a visa from 0 to 4 years old never had any issues with overstays at immigration but both parents had valid visas, now she started school so she has her own visa.

Yes, you will have to go to your home country and apply for a dependent visa. You might also need 500k for each of you

I ask the immigration officer if it’s bad that my baby has overstay. He was laughing at me 🤷🏼‍♀️ so my baby went in and out several times with overstay and never had any problems…

Now you need to go to home country

Obviously it would be ideal to get a visa for your child. However, it’s important to realize that under the age of 15 there are no penalties overstay in Thailand

If you want to get a DTV for your child you have to go back to your country of origin. Whether it's a dependent or new application, DTV can now only be applied for from the country where you have citizenship or permanent residency.