I don't edit in photoshop pretty much at all yet but here is how I would try to do it. I would merge the three photos together into one photo. I would have each princess on her own layer and then lay them out so the appear in the final image as you want them to. Once you have it the way you want it, after flattening the layers, resize the whole image into the finished size you want, the 1" by whatever. Hope that makes sense and helps some.
If you want, I can try and see if I can do anything with them. I've been watching an advanced course couse on photoshop so I can see if I have learned anything yet.