@Paul ****************
she can enter Thailand with an expired Thai passport. THAT'S WHAT SHE SHOULD DO.
AND now it's super easy to get a NEW Thai passport after she is in Thailand. In a few days it's issued for either 5 or 10 years. 1,000 to 1,500 Thai baht fee.
IF she enters as an Aussie... Then SHE needs to do a DTAC registration.