Family & de facto law, financial agreements, consent orders
There is no process in law, that I am aware of, by which a parent can disown a child. They can say that the child is disowned, never speak to them again, walk on the other side of the street or generally behave as a prat but if the parents name appears on the birth certificate, nothing is going to get it off there.
I am like a "bush lawyer' to many people I know and they frequently ask of me legal issues...and when they ask me about these issues (of wills) I always point out that many families have "black sheep'..and the grand/ parents tend to leave out these children....or other immediate family relatives from their wills as perhaps they may been estranged for many years. I always advise that they MUST never do this...I realise that this is a hard ask...but they MUST leave something to them in that will. this prevents many conflicts and perhaps even the contestation of those wills proceeding their passing