I don't love Breyer youth dolls. Out of the box they are just about useless as riders and are really only good as standing around prop dolls. Some of them are not even particularly good at that. Youth dolls take a lot of work to be good riders. Even then, they are somewhat delicate dolls.
Recently (OK, I had this doll WAY too long before I got around to fixing her) a youth doll came back to me with a broken leg. The way I made youth dolls is to take the legs off, cut the leg below the knee, drill a hole and super glue sculpting wire into the hole. I then wrap the leg with gauze and medical tape. This particular youth doll had the wire in her leg snap.
My first step was to get a sacrificial doll and steal one of her legs. I thought about replacing both legs but then I figured I would try out a repair instead. I unwrapped the broken leg and trimmed off a new piece of sculpting wire.
This next bit was a complete experiment. I spread some of the gel superglue on the wire protruding from the leg and up the wire from the original leg. Then I took a piece of gauze and wrapped it around and around so the gel glue squeezed out into the gauze. Yes, I did glue myself to the project at one point. It is almost impossible not to. My hope was that when this all dried and cured it would hold the leg on and also reinforce the part that bends.
The next step was to drill a hole in the new leg and add in the wire. I use Gorilla gel glue, which I have found is great for a variety of projects.
I got all the clothing back in place and did the stiches to hold the breeches under the foot. This make them look the way they should and also ensures that the pinned foot is very unlikely to come off. The doll is still fairly delicate, she doesn't have a lot of Breyer youth doll left to her, but she is back in one piece and ready to ride again.
Next was taking the original foot and boot and putting it on the new leg. I trimmed the ankle down a bit since it was too long (there is a lot of cutting involved with making youth dolls) and then I pushed the pin from the foot into the lower part of the new leg. Once the boot top was back up and glue in place again I had everything almost back together. Cutting off the feet and pinning them into the leg (literally) is how I can get youth dolls to have flexible feet.