Hi Jean. Your DD and mine sound very much alike. Both 9 1/2, L4's with lots of higher skills and sometimes too much enthusiasm to advance these talents.
Increasing the range of motion in one's back and shoulders is about stretching. How's her bridge? Are her arms by her ears, legs straight, and shoulders past vertical? The latter is by far the hardest do to with her limited range of motion in her shoulders. When she practices them, have her hold her shape a little longer, but also to use her legs to try to push her shoulders past her hands. As always, tummy in, butt tight.
To stretch the shoulders, she should warm up with lots of small and large windmills in both directions. Also, Arm swings front and back. The arm swings should be as far as she can reach. This action is a dynamic stretch, so don't hold any swings, just swing strong, and close to the body in a variety of directions. Really get these muscles warm and tired before doing any static stretches. Cold muscles don't stretch. They react more like rubber bands. Whereas warm/tired muscles will elongate before retracting.
Once warm, cross one arm straight across the line of the shoulder, holding it horizontal, and using the other hand to push the arm (above the elbow) closer to the body. Hold for 15 seconds, switch to the other arm. Repeat 3 times.
Then, raise one arm, always palm to the cieling, reach over the head as far as she can go, leaning into the direction of the stretch. Hold the longest range for 10 seconds, then switch arms. Repeat 3 times. (can also be done while sitting or in a straddle, the other hand can grab the wrist and pull the arm farther)
Lastly, sitting up on the floor, legs straight in front of her, have her put both arms straight behind, shoulder width apart, elbows locked, palms down. Then slowly lay back, reaching and extending the arms farther behind her. Hold the tightest position for 20 seconds, rest for 15, then do another 20.
All these stretches can be done at anytime -- even during Zake and Cody. But to increase her range of motion, they need to become a daily routine. Just once in a while doesn't really cut it when it comes to shoulders.
(Saftey tip: Don't help with any static stretches like I see some do on You tube. This is dangerous territory.)
Lastly, when she does her handstands, RO, and ROBHS, try to get her to consiously reach her arms up high and close to her ears. This is a problem my dd has as well. Our couch suggests that when reaching up, if she can get into the habit of touching her finger tips together, it will help remind her to get her arms up. It also trains the motion so the hands and fingers look nicer and more ballet-like when doing the skills.
Of course -- easier said then done. Old habits are hard to break.
Hope it helps,
Tim
Check out:
http://www.drillsandskills.com/
It has a nice section on stretching.