I'm a parent and I can relate because the same thing happened to me. The younger one didn't actually beat the older one, but everyone knew it was coming. The inevitable happened, and the older one quit. That was OK, because she moved on to other sports such as soccer and volleyball, yet still was very supportive of her younger sister in the gym. I was very lucky there was no resentment. But, it also happened to another family in our gym. Same thing, two sisters, two years apart, and the younger one was considered the better gymnast. The older one stuck it out and stuck it out, and it didn't seem to bother her that her sister caught up with her. It's been a few years now and the older one grew, gained a lot of strength and skills, and she is now the stronger gymnast with the higher scores. So, I guess your daughters' outcome is up to each of them individually. If they really love it, they will stick with it no matter what, and if they work hard enough, they'll both be good at gymnastics. If one is better at one event, the other might be better at something else. If one decides to move on, there will be other things on the horizon that she will excel in, and your job as a parent is to support them both and encourage them no matter what they do.