This is not unique to JWs vs Non JWs it happend to my family and all involve are JWs.
Basically the old person goes senile and entrust their estate to some body (in our case a person at their hall they liked). The person gets the Dr to declare the old person unable to give informed consent so now the trust takes over is in effect giving the old person have the same legal rights as a child.
It is a flaw in the court system not JWs. Many people with older relatives get scamed like this. The money gets frittered by the trust leaving an empty will full of things already sold. The watchtower says they can't get involved and don't want the money (legally they are so barracaded you can't get them out of brooklyn).