Normal
First off i would be concerned about the children and if they are not safe call in the authorities. I know that is not ideal but better than something horrible happening. Is your brother inlaw any more responsible? Secondly both your father and your sister are adults if he already got a settlement does he still have any standing to get more? I would say get an attorney that deals in financial matters and find a way to protect what your mom has left. I don't have knowledge of the law but i would think a savvy attorney would have some ideas. Since your father and sister are adults i am not sure you can do anything unless she has committed a crime against you or your mom. Ask the attorney if there is fraud involved. I am sorry you have to go through this and i hope some of the more experienced members can give you some good ideas. Good luck and prayers are with you.