I just reread my post - nowhere in there did I say I thought you should have the entire train to yourself. I was talking about your apparent desire to have an empty car
behind you. That's a big personal space need!
I get that it'd be uncomfortable for some folks to be bumping knees with a stranger - that's why I suggested that if it's an issue for you, you should mention it to a CM. After all, the CM might have thought you two would appreciate the company. I know I would have!
(And it's highly unlikely the stranger would have molested you, with a family sitting right there.)
However I still don't get being unhappy that there was a family in the car
behind you. It's a different car! So what if they didn't space you all out evenly through the train? They're not in the car with you.