We applied and understood it as the dependent don´t have to pay 50.000 bath for the visa. We are waiting for our visas. Did you have to visit BOI in Bangkok for the visa stamp or could you get it in any immigration office if you are in Thailand ?
He can buy a re-entry on his single Non-O 90 days so he don´t have to start all over. But he only have the remaining days left on his first arrival on the Non O.