They needed to see that the choice was not "gay daughter lives with us vs. straight daughter lives with us" but "gay daughter lives with us and we respect her choice" vs. "gay daughter cuts us out of her life". Because they thought they had the power -- she *needed* them. They had to see she didn't. And she needed to understand all of the things that they'd given her, which she'd be giving up if she gave up on them.

I had a friend who failed out of his first year of college. His parents offered to pay for the subsequent years, *if* he could be reaccepted after going to community college for a year. They'd pay tuition. But everything else, he had to pay for. On the salary of a pizza maker. I've never seen anyone so motivated to study hard and get good grades! Because he quickly discovered being on your own with a minimum wage job is no fun.