You are allowed to have dependents on the DTV visa. You would apply first, once you are approved your family members can apply as dependents and should not require the additional financial requirements. You would need to check with the embassy you would be applying at.
based on this screenshot it sounds like you should be able to apply with 65K each per month. Once you get to Thailand, you must have the 800k in a bank account for a minimum of 60 days before you can do your one year extension. The 800k must remain in the bank for 3 months after application, it can then drop to 400k and must go back up to 800k 2 months before applying the following year.
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