The girl who had been chosen at tryouts to become a cheerleader, when Amber never came, was Kyla Leeson.
In the original reality, Kyla did try out for cheerleading. But she'd been rejected for it, and had never looked back. She had eventually migrated into the geek crowd at school.
But now because Amber wasn't there, Kyla had now been a cheerleader from the very beginning.