One major Key for the girls is to teach them to get the leg energy moving upward and strongly and then shoot from that. Girls tend NOT to jump upward powerfully, as boys do, so they have to be encouraged to do so.
The other main Key is to learn to master the Release motion. They can learn to fire off the Release quickly and strongly, what I now call a "Full out" Release motion, a pushing action, to the end-of-the-arm, at the same speed and force each time, with relaxed wrist and hand, as you see in the video. It's like a "spring-loaded mechanism." You cock the arm to the Set Point, and then "pull the trigger," letting it fly, aimed high, full out. By full out, I mean about 70-75% of max. speed and force. It's a manageable motion that will not hurt their arms, but it IS quite quick and strong. It's not a slow motion thing. That gives them a quick Release. The hand will "flop" when the Release push is done strongly, since aim is to have the wrist totally relaxed.
The Release is learned at the "Pure Release Distance" (PRD), where, with just a little bit of UpForce for girls of this age, but the same amount every time, they can practice and learn the full-out Release over and over. Don't make the U/F a variable, but I think most of them, especially the younger ones, will need to use some legs to give them the necessary power, along with the Release, to get the bottom of the ball up to 11 or 12 feet. It needs to be an automatic, repeatable motion, sending the ball high and soft to dead center.
They should find the Release motion they want first, and then adjust their distance so it flies high and true. Practice it over and over. They should be able to make 5, 10, 20 or more in a row once they have this down. Then remind them to return to that PRD every time they practice shooting, learning and re-learning the Release over and over until it becomes the default, automatic, a no-brainer. Once the Release is mastered to some degree, then, as they move back, they will need to add leg power or the always-the-same Release will not be enough. The use of U/F will become a necessity, which is great because it gives power, the quick Release, the height they want ... and it STABILIZES!
I hope this helps a little more. Keep it simple. Explore it with them. Help them discover the great shooter within each of them. Let me know what works for them. Even if a girl is small, she can generate a lot of force with those strong muscles of the middle and lower body. It might have to be kind of explosive, but it can be learned. Once the power is there, then it's just a matter of direction and varying arch to control distance.