Thank you for asking, in fact I already answered some of your questions:
1) I would ask the state/government to hold them accountable. Beyond that I would forgive. My family, me included, have forgiven the doctor who committed malpractice and most likely took away valuable months if not years from my dad. The doctor lost his license to practice for good reason, he performed poorly and did not take his job seriously enough. That is enough. I bet the person who ran a red light has done jail time. All other things are forgivable and can be managed by the family just as we have done.
2) see 1)
Your point Re taxes is moot. If the law sees the annual payments for the daughter as a gross payment then taxes are rightly due, just as your deceased brother had to pay income taxes before making payments to his daughter. If the law decides those are net payments then they should not be taxed. Everything else is bullshit and you should sue the IRS or live in a jurisdiction where reasonable practices are applied.