^^I would like to be wrong about the victims and their families signing their rights away, and the reports I read from what I remember referred to these people giving up their court cases etc. Fundamentally thats why I am asking you to point em towards the articles that gave you the impression that they had not, If you want me to take you word for it, fair enough.
At the heart of the issue is the question you asked earlier 'where in thailand do you do for the truth', well at the end of the day you have to use the tools that are available, and in thailand its the same as anywhere else.
You can sit back and wait for the government to give you as much truth as it wants
You could use the official information act
You can use the courts, probably the best place to ask questions, as at the very least you are putting those who want to lie in a compromising position which for people high up in the patronage networks is not much of an issue, unless someone in another network decided it will. But use the often courts you must demonstrate a loss for which you require financial compensation in order to start the case. you cannot do this if you have accepted a full and final compensation payment.
You can argue with justification that these organisation are compromised, the OFA is administered by the Office of the Primeminister and well the courts.... But even if they are and you loose your cases, you have forced these people to come out into the open, lie and deceive; which is hard to do without damaging their political and social reputation.