Any recommendations for prenup that protect American assets?

Hi, I posted on here a while ago regarding my Australian father passing passing away in Thailand. I need an international lawyer that won’t charge an arm and a leg. My brother is married to a Thai but resides in Australia. My father had a will here in Australia. My brother took control of everything of my fathers, withdrew all funds from his accounts, (illegally) forging his signature and simply said he gave away all his assets. I also want a title search done on land and a company name search if that’s possible.