Ultimately, there is no blackmail that is escape proof. It is the blackmailer that makes the choices easier to give in to. If someone is willing to take a certain hit but, forever remove the threat, then the blackmailer loses power.
In Aiden's case the solution is boarding school or later in game talk to her best buddy Morello and have a horse head delivered to Aiden's Uncle. He will get the idea real fast no matter how much he thinks he is a big shot lawyer.
In Bennett's case he will need extensive reconstructive knee surgery.
Sophia will be indebted to Morello and it will be a totally different path of corruption. However. the debt would be hers and the guilt hers. Unlike the situation with Liam where he is doing nada and getting his debt cleared. He does not see a consequence except for a few days stress. Something
KillJoys is accurate in pointing out.
However, this is not our game. It is L&P's game and he is driving a different car on a different route and we are just sightseers.