I've received an email detailing anothers struggle against a sociopath that is consuming the lives of thier parents. I sympathize with their attempts at legal intervention because my own were fruitless. My impression of the legal authorities is they assume both parties are lying for their own ends. And, in the authorities defense, it does appear that most people believe that lying is acceptable if it can be gotten away with. If the authorities do not have overwhelming evidence they do not appear to rule in anyones favor and choose to do nothing.
Here's another aspect to consider. If you read Martha Stout's book you could conclude that many business people, politicians, police, lawyers and maybe judges are possibly sociopaths. Now I'm not a big advocate of conspiracy theories but given the types of occupations sociopaths gravitate towards it's almost looking like they could be running the show, to a large extent. This being the case, it would not be in their best interest to seek legal precidents against anyone that could be a sociopath. Please remember this is just a thought of mine and is certainly not based on any research.
Now, getting back to the question of whether there is any way to battle a sociopath that is manipulating parents or anyone else, whether it be parents, other relatives or friends, you have to let the others come to their own conclusions. Sociopaths are just too good at lying and making others believe them. Many times people have to loose most of what they have or be abused to a great extent before they come to their own conclusion and say enough is enough! Trying to convince someone that a sociopath is manipulating them is like banging our head against the proverbial wall. People that are being manipulated have difficulty conceiving how someone could have no conscience. You can explain it as much as you want but without a reference frame to what sociopaths are capable of they can't understand it until it's already happened to them. Then they may still be in denial.