Crap. A Thai marriage (with notarised translation of the Thai marriage certificate) is legal in Australia. It is illegal to marry in Australia if you are already legally married.
The partner might be a veteran and the surviving spouse may get nothing. The sytem is pretty complicated. It depends on the status of the veteran. eg if the veteran is Gold Card TPI or EDA, the surviving partner would automaticallky receive a War Widow(er) pension fron DVA refardless of the cause of the veterans death, If the veteran dies and his cause of death can be related to service or cause of death is a DVA accepted condition then the partner will also get the War Widows pension. If the veteran is GoldCard (but not TPI/EDA) or White Card or no card and the cause of death is unrelated to service then partner is entitled to nothing.
You national licence (you do not have an international licence - it is an international drivers permit (IDP) which is not a licence at all. And you need a medical certificate.