If she’s gone through all of these things and she’s done all the massage and she’s done all the stretching, seen some improvements but then stopped, it may be time to get a plain film x-ray of her ankle. So looking at the ankle in a pointed position and just seeing if there’s any bony restriction at the back.
We all have something called a posterior tubercle which is at the back, some people have a big one and some people have a whole extra bone, it’s called an Os Trigonum and approximately 20% of people actually have one, it can block range in the back of the ankle. So you need to know if this is actually blocking her range. Often it can be worked around if it’s not causing any pain; dancers can learn to work with it. You can work on maximising the range as much as possible through the middle part of the foot and by releasing up deep into the back of the calf. If there is pain at the back and if she is looking at a professional career, it is possible in some cases to have that removed, but obviously, surgery needs to be avoided at all costs. But some people do have this procedure done and it frees up quite a bit of range at the back of the ankle.
And also take note if she has any hyperextension in her knees. Sometimes people have enough ankle range but if their needs are a little hyperextended that actually needs slightly more range to really get up onto the shoes, especially standing in second.