Yes, the dolls break REALLY EASILY. Luckily, there is an ingenious and very simple fix that my 4 year old devised this morning.
DO NOT GLUE THEM. They won't maintain the ability to bend. Instead, my daughter suggested we sew her back together. That way "She can bend around the thread!"
And it works. I used a standard sewing needle and standard thread. I started from the inside of the "skirt" so it didn't leave an outside knot. And 5 minutes later, Elsa's "surgery" was complete, and we had a fully working doll again. Good as new. And if the thread breaks again, just re-sew it.