@Marly **********
you transfer in the 500K baht from overseas into a thai bank account in your name only and then you can apply for the 90 day non-O visa based on raising a foreign child here. (there is no amount of time the money needs to be in the account to get the 90 day non-O visa issued)
To get the year extension you need to have the funds in your thai bank account for 30 days for the first yearly extension and 3 months for every yearly extension after that