I know how it is when you have a show in your head and for some reason numbers or kids don't materialize! Willy Wonka JR and especially the KIds version is a great show, but it would be a challenge to do with 10-11 kids. (Not impossible, but a challenge!) Oompa Loompas would have to play several roles (grandparents, candy kids etc.) and you might have to have staff or community member or theatre company alumni to play a few short roles such as Phineous Trout. Any possibility of using little brothers and sisters as Ooompa Loompas? If you full-on costume, changes might be tricky. If you told me you had 15 I could safely say your task might be easier. Any other shows in your vision? KIDS versions run 30-40 minutes and usually have smaller casts and easier to allow kids several roles.