I know this is a little too late to apply to this situation, but please consider it for any situation in the future:
Do not bother even considering cutting with kids... of any kind...(Excepting cutting out junk food, soda, white sugars etc, that they really shouldn't be having anyway). The most important thing to them is proper developmental growth, winning a medal now isn't worth impairing their development in any way. Especially at their low weight, the ratio of impact of losing just a few lbs is massive on their body.
A very commonly neglected aspect of shocking your body with a weight cut of solid %, is that the state it puts your body in, does not just last for a day, it lasts for weeks. The way it can effect your body's use and storage of fats, glucose, insulin, and by proxy all functions of your body and aspects of athletic performance can be hindered far more than the benefits a weight cut can often offer. Especially at her age, anything that could imbalance metabolic stability is a poor idea.
I have researched weight cutting extensively, and am near competition of an in depth manual on the topic including health concerns of various methods and I can tell you for sure, at her age weight growth spurts are not abnormal, and it would be a terrible thing for her to be cutting weight. For both her future health and her future as a jiujitsu competitor cutting weight will hinder her development. For her to have her full potential in healthy growth and development is much better overall than being able to bully a tournament by being in the top of the weight cap instead of the bottom.
Cora is super skilled, and it's much better to be in the middle of a division and skilled enough to where a few lbs is no difference at all, than relying on having to be the biggest in it. I know in this case you wanted her to stay in the division so she would have MORE competition, but again it isn't worth the drawbacks.
If your reading this and still saying 'yeah but she really wants to compete and win so we will cut this one time even though it might be...', just stop there and ask yourself whats important -- this ONE medal or ONE event with good competition, or all the ones in the future she will get by not having her growth and development impaired.
Cora is a future world champion, hurdles like this might be frustrating now, but shes got a long and bright future, and girls/womans bjj is only getting started. ;]