@Trevor ******
suggest you have him visit Jomtien immigration and ask IF...IF...IF he can once again get the one year extension and the requirements for it.
He has to meet and prove the financial requirement too.
And yes Jomtien most likely will need to see proof of the 400,000 Thb in the bank when he returns one month later after the Under Consideration period to get the full year stamp in his passport.
Bottom line...he may or may not be allowed to even do this as he is now under a COVID extension and had a Non O based Thai child support visa before.
He may need to leave Thailand.
Good Luck.