So... This is one of those drills that can help... Or not... The good news is that it is cheap to do at home, the bad news is that unchecked it could hurt your daughter. So please, take my suggestion and do it safely, and only if you think it applies to her.
If you have a carpeted area in your home, go to the hardware store and ask them for furniture movers. They are plastic flat pieces that are padded on one side and polished plastic on the other.
Go home and take 1 out, have your daughter kneel on both knees. Take one foot out in front of her (this should look like the split stretch at this point). Rest her heel on the mover, and control the slide into the splits.
My suggestion is that you stand next to her or she does it near a couch so she can catch herself if she goes too fast. If she loses control and slips while flexing her muscles she may tear her muscles if she is not prepared for the motion.
She should do this with both legs until she can squeeze all the way down on both sides. If it begins to hurt, stop for a day or two depending on how fast she heals, and try again.
The purpose of this is to increase her active range of motion - in other words, the range she can split while still using her muscles.
As I'm writing this I'm thinking you could probably use a towel on a wood or tile floor, too, but it may offer more friction so it won't be as smooth... Maybe you can try with a towel or shirt first to see if she even needs the active flexibility...
Hope that helps!
Ryan