Some advice on how to deal with a "interesting" brother in law

[NuclearEnergy]

First one question, what did his wife/your sister have to say/do when she heard his thoughts? That may guide your future actions more than anything. 

My take, your parents money and how they spend it is none of his business. These are not "His" parents, they are in laws. With the divorce rate the way it is there is a good chance that he wouldn't be around to see any money anyway. Plus, parents owe nothing to the children. What they choose to give is just that, their choice. They may have to spend a substantial part of, or all of, their wealth prior to their death. Shit happens. 

I'd probably have said to him "It's not your money and you need to keep your opinions to yourself. If you are not able to tell my parents directly what you think they need to do, there may be a way that your opinions can be forwarded on to them."

She just sits there silently like I do, and doesn't really contribute to the conversation. It's sort of a marriage where he is always right and she is just some airhead in his eyes.

And yes! I couldn't agree more. Children aren't entitled to ANYTHING. I don't care who you are. However, most parents do leave behind things for their children. And to me honestly, I really don't care either way. [My parents have told us that they will be leaving things for each of us. But like I have said, it's really nothing that concerns me or that I'm anxious about] Also, that is true about divorce. However, apparently after 7 years it is more likely you are in it for the long run with a marriage. I can't find the study, but if I do I will for sure PM it to you

He is very nosy when it comes to immediate family matters. Not really sure why. He also thinks he knows EVERYTHING that is going on with my family, my Dad's family and my Mothers family. But he really doesn't. 

And that is a pretty good solution. But boy, I wish I could muster up that kind of courage. If I am ever in this situation I'll try to tell him it's none of his fucking business. I will go about it kindly, of course.

However, like I have said previously on here; I just find it incredibly disturbing that he seems to have really thought about this.