Work up to this in 2.5 cm increments......Stand on on layer of folding mat, lift r/o front leg with ars raied over your head.....Let your self fall forward, touch front foot with nearly straight leg, kick back leg hard and straight up behind you, fall off your front foot while you push with it, finish in a feet late to gether round-off.......get used to drill and increase height to 5cm to allow for more fall speed.
At this point you should be seeing enough push from the hands and enough leg speed to produce a reasonable snap down...If not go up another 2.5 cm. to get more power. Have to kid start the following tumbling session with ten round-off snap downs. Because of the lack of run and the consistency created by falling of the mat, the round-off will be; easier to train due to fewer variables so you can coach the same skill two times in a row
Have a more powerful snap down because of all the compensating taking place with out the run
Better direction which means less energy bouncing from side to side
better posture (if they fall, kick/push) which gives more power during the push off from hands
It's your choice after that...If you have her run into the r/o after warming up as I suggest, she will work the snap down muscles out of habit, and actually snap thru into a ground pounding earth shattering lightning fast back handspring. If I were you I wouldn't let her run too far, and since she's not experienced enough to know to adjust her snap down to compensate for flips vs. tuck saltos, I'd appreciate it if you'd spot her as the first one will be the best one she's ever done if she follows through (most do)
but it could be so fast she freaks out ( about 1 in 40 ). So keep her safe and always go to that drill until you can watch them as they tumble straight toward you, and correct if you see anything other that the posture you'd like to see in a handstand....it should ALL go straight over the top as if on balance beam. And no more r/o salto tucks until they have about 2-3 hundred r/o flips so they can develope muscle memory.