1. She helped it happen for me to drive a car.
2. He let it happen to break the window.
(What about these sentences? Can we use these structure?)
These, too, are quite awkward and the phrasing would not be used. Try these instead:
1. I wanted to drive a car, and she helped make it happen.
2. He didn't stop the children from playing ball in the street, and they broke the neighbor's window.