Adoption and narcissism

I’m sorry for the pain you’ve experienced from your parents. It was cruel of them to hide the facts of your birth and to treat you poorly. Sounds like your mother has been jealous of you. It’s beyond sad that you didn’t receive love and kindness. The best indicator of what’s to come is often what has already happened, your parents have shown you who they are and how they’ll treat you. Please don’t sign up for more, they aren’t changing except to possibly get worse. Build your life around people who bring positive things to it. Spend your time on enjoyable, fulfilling activities. You’ll be happier and feel love from others. I hope you won’t continue to go to the well, there’s no water there

I'm not sure of how the Will issue works in Australia, but contesting a Will in the U.S. happens only when the writer of the Will passes away. In your case it sounds like both parents will first need to pass (assuming they have included each other in their own individual Wills). After they pass they can't control who contests their Will. You would be able to contest each Will after each one passes. Each person has their own Will, it is not done jointly.

Are you maybe referring to PoA? Again, each person needs their own PoA individually. Is your brother PoA for each of your parents? In the U.S. if you suspect fraud or abuse by a PoA you can pursue the matter in court but you will need to provide evidence for an attorney to consider if your case is strong enough. Again, it would need to be for each individual (your mom and dad, separately).

If your parents are each still mentally competent, then you can't really do anything until that point, which is when your brother's PoA authority (again, for each individual parent) would become active.